Updated: 01/10/2018

If you’ve been looking into supplements for rapid weight loss, perhaps you’ve come across a product called Fastin-XR. Fastin-XR, also known as Fastin, is a high-level weight loss intensifier made by a company called Hi-Tech Pharmaceuticals. If you’ve heard of Fastin but are overwhelmed by the amount of information available, fear not: we’ve researched the ingredients, side effects, and science behind Fastin so that you can make an informed decision before purchasing the product. As always, we will give you our thoughts as well as the bottom line on the product.

Fastin Readers: Click here to find out why we're giving away samples of our product, Burn HD.

What is Fastin?

Fastin is a proprietary compound and pharmaceutical-grade weight loss formula. While Fastin-XR is available over-the-counter (OTC), the formula was designed to be administered to obese people to achieve medically-necessary weight loss.

The name Fastin of the supplement alludes to its function: Fastin can assist the user with rapid weight loss.

Fastin is made by a company called Hi-Tech Pharmaceuticals, based in Norcross, Georgia. The CEO of the company is named Jared Wheat.

Hi-Tech Pharmaceuticals manufactures some weight-loss products including CarniSlim, CoffeeTrim, and SadieTrim. They also have several other formulations in development, including Fastin for Her and a weight-loss product called Black Pirahna.

As of now, Fastin-XR appears to be Hi-Tech’s signature weight-loss formula. It distinguishes itself from the original formula by being more potent. The “XR” stands for “extended release.” Compared to their other products, Fastin-XR is probably the most-aggressive blend of stimulants, while products such as CarniSlim and CoffeeTrim are touted as “weight-loss support.”

As with many weight loss products, people tend to ask, “Does it work in the long term?” Fastin is a somewhat-unproven product, and most of the available information on Fastin would confirm this. We’ll see the latest data on Fastin in full later in the article. The million-dollar question, as with most any weight loss product is, “Is Fastin right for me?”

We’ll answer these questions and more in more detail in the paragraphs below. Keep reading for a full overview on Fastin and its potential as a weight loss product.

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Fastin Ingredients

Fastin-RX uses an extensive list of ingredients. As with many fat-burners and weight-loss pills, Fastin leans heavily on caffeine. Here are some of the other ingredients in Fastin-RX, along with the science behind each:

1. Thermo-Rx

For metabolic and blood pressure regulations, Thermo-RX is commonly used. It primarily assists in blood pressure elevation. [1]

2. Phenylethylamine HCL

Phenylethylamine HCL helps to regulate the thyroid glands in the body. An overactive or under-active thyroid gland is never a good thing. The studies behind this one have seen mixed results. [2]

3. Methylsynephrine HCL

This compound is thermogenic. It rapidly elevates heart rate and metabolism. Some evidence has shown initial negative results. Further studies are necessary, especially as they may relate to the long-term benefits and effects of Methylsynephrine HCL. [3]

4. Theobromine Anhydrous

This assists in mental health, primarily neurological disorders. Unlike most forms of caffeine, it contains far less concentrated amounts, and the dosage or intake can be monitored much more accurately. Theobromine has also been reported to clear the mind when repeatedly taken throughout the day. To date, the results and opinions in the health community have been mixed. [4]

Because Fastin contains caffeine, the dosing benefits of including theobromine are somewhat mitigated.

5. 1,3-Dimethylamine HCL

The fat-burning and lipolytic potential here are unique. 3-Dimethylamine HCL is contained in many dietary supplements. [5]

6. Synephrine HCL


Keep two things in mind in the case of Synephrine HCL: while it has promoted weight loss and successfully achieved it in some individuals, in numerous cases, it has caused adverse side effects. [3]

We suggest you exercise caution before consuming products containing Synephrine HCL.

7. Yohimbine HCL

Yohimbine is often used as an erectile dysfunction prescription drug or testosterone booster but has many other uses. The positive and potentially-negative effects of Yohimbine are well-documented. [6]

8. N-methyl-b-phenylethylamine HCL

This ingredient primarily consists of antidepressants and stimulates beta receptor activity. It also slows down one’s heartbeat, a major concern noted among those who have used it.

Aside from the concerns over slowing down heart rate, another thing we don’t like about this compound is its potential for addiction. [7]


Educate yourself and consult with your doctor before taking products containing N-methyl-b-phenylethylamine HCL or any compound that has the potential to slow your heart rate or promote addiction. [8]

9. Caffeine

Caffeine is a staple in weight-loss and fat-loss supplements, and Fastin is no different. Fastin contains 150-200 milligrams of caffeine, depending on the formulation, and one cup of regular coffee contains about 95 mg.

Too much caffeine can, of course, be a problem, and many people tend to take in excessive amounts by not monitoring their caffeine intake closely. [9]

Fastin was introduced around 2010 from Hi-Tech Pharmaceuticals. The supplement is sold through the official website and established retailers. We like a few of the ingredients and that we found some positive customer comments, but read on…

Fastin Customer Testimonials

What is Beta-methylphenethylamine?

The key ingredient that deserves special consideration is beta-methylphenethylamine.

Also known as BMPEA, beta-methylphenethylamine is a member of the phenethylamine family of chemicals, which also includes amphetamines and hallucinogens like mescaline. firth

According to University of California San Diego professor of chemistry Dionicio Siegel, who studies phenethylamines, this class of substances can target some brain receptors controlling energy, but also have LSD-like effects. [10]

There are serious health concerns regarding BMPEA. From an NBC News report:

BMPEA has never been tested in people for safety or efficacy.

BMPEA has been shown to raise blood pressure and heart rates in dogs and cats. It is classified as a doping agent by the World Anti-Doping Agency because it is closely related to amphetamine.

Hi-Tech Pharmaceuticals, a manufacturer of supplements containing BMPEA and a supplier to other supplement makers, says it has conducted a clinical trial of a supplement containing it on ten men. According to the results, the subjects’ heart rates increased by 11 beats per minute, and systolic blood pressure rose 22 points. Hi-Tech paid for that study.

We would advise extreme caution before taking any product that contains BMPEA. There is simply not enough clinical evidence that BMPEA is safe.

Nutrition Facts

Fastin Nutrition Facts

Fastin comes in a 245-375 mg per tablet dose, depending on the formulation.

fastin nutrition

There are no minimum daily values for any of the ingredients in Fastin, and there are no vitamins or minerals.

Given the relatively high dose of caffeine in each Fastin pill, we think it would be wise to assess your caffeine tolerance before ingesting a tablet. The “Fastin How to Use” section includes information on how to assess your tolerance.

What Does Fastin Do?

Fastin claims to boost metabolism, and given the lengthy list of stimulants in the ingredients list, we think it probably works as a potent energy booster in many people. There is not a lot of hard data available to back this claim.

Hi-Tech Pharmaceuticals advertises Fastin as an energy booster and an appetite suppressant, and we believe that’s true in fashion. Our concern is jitters and “false energy,” as there is nothing within the formula that specifically burns fat and preserves lean muscle. For example, Yohimbine is often put into testosterone-boosting supplements and reputed as a libido booster, and but Yohimbine’s direct effect on body composition and fat loss is less well-established.

One study on the body composition and exercise performance of men’s soccer players [11] found the following:

The athletes (20 top-level male soccer players) were allocated to two randomly assigned trials. Subjects in the yohimbine group orally ingested tablets that contains yohimbine at a dose of 20 milligrams per day in two equal doses for 21 days. Subjects in the placebo group ingested an equal number of identical-looking pills that contained cellulose.

No subject reported any side effects from yohimbine. The results of the current study indicate that supplementation with yohimbine combined with resistance training does not significantly alter the body mass, muscle mass, or performance indicators in professional soccer players.

Based on this study, it appears Yohimbine does have an impact on fat loss. But this study was conducted on professional soccer players without account for their massive energy deficits. Professional soccer players account for a fractional portion of the population. This study is not without merit, but it was done on a statistically-tiny portion of the population.

And even if Yohimbine is an effective ingredient, given the list of ingredients with adverse side effects, we would be reluctant to give Fastin our full endorsement.

While this potent stimulant cocktail might give a sluggish metabolism a kick in the seat of the pants, anyone using Fastin or a similar formulation needs to be concerned about the considerable list of potential side effects. We cover those in detail below.

Does It Work?

Does Fastin Work?

In our review, we have determined that like many weight-loss products, Fastin can be effective if used properly. But this assumes a number of things and ignores the fact that a significant number of users have had problems with Fastin.

It should go without saying that there is no such thing as a miracle pill that will allow you to lose body fat with no changes to your diet, exercise plan, and lifestyle. Those factors are the most important, and supplements can be viewed as a finishing touch on an otherwise sound weight-loss plan.

Reviews on Fastin have been notably mixed.
Does Fastin Work

In clinical settings, when combined with controlled calorie and carbohydrate intakes, Fastin has proven to be successful in helping obese people lose substantial amounts of weight. But the effectiveness of the dietary approaches themselves also needs to be taken into account. [12] [13]

How Does Fastin Work?

Fastin is otherwise known by the generic name phentermine. Phentermine is an amphetamine-like prescription medication primarily used to suppress appetite. This is the main mechanism through which people lose weight while using Fastin or phentermine, in conjunction with an intelligent weight loss program. [14]

Fastin also features some ingredients that may individually have fat-burning effects. As noted above, you can find studies which connect Yohimbine with fat loss. Caffeine is well-known for its metabolic and thermogenic properties.

But we suspect Fastin works on the flawed premise that “more” equates “better.” There is very little science linking the fat-burning properties of phenylethylamine and theobromine, for example. Given the lack of science, it appears that some compounds with fat-burning or thermogenic potential were simply mixed. Thus, it’s hard to determine which compounds are effective for fat loss or weight loss and which are not.

Furthermore, and this will be addressed in full below, but some of the compounds within Fastin – such as Methylsynephrine HCL – have a litany of adverse side effects. [15]

FDA Complaints

FDA Complaints

This is from the release by the FDA (Food and Drug Administration) on Methlsynephrine:

In recent years, FDA has identified some sports products that are marketed as dietary supplements but contain substances that don’t qualify as dietary ingredients and may pose health risks to consumers.

Methylsynephrine has joined the list of substances that are the subject of FDA warning letters to marketers of sports products.

The FDA explained further on a webpage linking to the warning letters:

“Methylsynephrine is not approved as a food additive or prior sanctioned for use in dietary supplements,” FDA stated in the warning letters. “Further, FDA’s review of this substance does not identify a basis to conclude that the substance is GRAS [generally recognized as safe] for use in food.”

The takeaway from this is to be very careful with the supplements you select. Many manufacturers try to pass off unsafe ingredients as safe to consume. We recommend that you always talk to your doctor before considering any supplement with effects this potent.

Lastly, it goes without saying that no weight loss supplement works without a smart, calorie-controlled diet plan. We like diets such as the Paleo Diet and the Ketogenic Diet, both of which encourage more natural food choices and less processed sugar.

Side Effects

Does Fastin Have Side Effects?

Fastin does have some reported side effects. Here are some specific concerns, broken down into key categories:

Anorectic Effect

Tolerance to the anorectic effect, or almost complete loss of appetite, usually develops within a few weeks of phentermine use. When this occurs, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued. [16]


Two commonly reported side effects of Phentermine are tachycardia (rapid heart rate) and elevated blood pressure.

Other reported side effects include regurgitant cardiac valvular disease, primary pulmonary hypertension, palpitations,  precordial pain, ischemic events, angina, myocardial infarction, and even cardiac arrest and failure.

Central Nervous System

Phentermine is intended to stimulate the Central Nervous System (CNS), the perceived and actual levels of stimulation vary greatly from user to user. Some have claimed improved focus and energy, while others have reported severe jitters, trembling, and blurred vision.

Overstimulation is a common occurrence with the use of stimulant cocktails such as Fastin-XR. When an individual is said to be overstimulated, he or she has trouble focusing and completing routine tasks. Fastin’s similarity to amphetamines has led many users and clinicians to report overstimulation in both regular and extreme cases. [16]

In this vein, hyperreflexia is a concern. As the name implies, one’s reflexes become hyperactive. While quick reflexes are desirable, particularly in sports, a chronically-overstimulated nervous system is not desirable. Stimulant blends such as Fastin-XR can burn out motor neurons and condition a person to rely upon stimulants for normal CNS response. [17]

Another one of the most commonly-reported side effects of Fastin-XR is insomnia and difficulty getting to sleep.  [18] From the Phentermine website:

Throughout the day, phentermine stimulates the brain to be more efficient and alert, increasing energy levels and concentration, but these enhanced levels of alertness can then interfere with your body’s ability to sleep, often despite feelings of tiredness. Some people believe that phentermine may inhibit the release of melatonin, the hormone which is released by the onset of darkness to bring about sleep. However, this is not thought to be the cause of insomnia from phentermine. Instead, it is more likely that the enhanced alertness which phentermine causes by stimulating the central nervous system inhibits the ability to sleep, despite the release of melatonin.

Lastly, Tachyphylaxis is the continued or repeated exposure to a drug that may lead to a weak pharmacological response. This is particularly true in drugs such as phentermine, which targets the CNS. [19]


Phentermine has been reported to cause some gastrointestinal problems including vomiting, nausea, and even gastrointestinal bleeding. [20]


Phentermine itself is not a common allergen, but any of the ingredients can trigger an allergic response in a person. Phentermine is known to cause tingling and skin flushing in some individuals. Urticaria (hives) is a reported side effect in some cases.


Phentermine has been reported to induce loss of libido and cause impotence in some individuals. [21]

The full list of side effects associated with Fastin is quite long. [22]

Depression and Psychological

There are no clinical trials examining the link between Fastin and depression. However, Phentermine is chemically-similar to amphetamine, and abuse of amphetamines and related drugs may be associated with intense psychological dependence. There are reports of patients who have increased the dosage to many times that recommended. Abrupt cessation following prolonged high dosage administration can result in extreme fatigue and depression.  [16]

Depression and Psychological
is a general dissatisfaction with life. While no clinical trials have linked phentermine or Fastin to dysphoria, stimulants – particularly potent ones like phentermine – should not be used to deal with general unhappiness. Using Fastin or any phentermine product as a mood booster is a recipe for disaster.

We recommend that you talk to your doctor about Fastin before taking it or any powerful supplement.

Fastin Health Risks

The FDA contacted Hi-Tech Pharmaceuticals in 2015, warning them about falsifying Nutrition Label information in statement dismissing Methylsynephrine as a dietary ingredient. [23]

There are always health risks associated with excessive caffeine intake. One 245 mg tablet of Fastin contains about a cup and half of coffee. If someone were to take Fastin 3-4 times per day, their caffeine intake could quickly spiral out of control.

A study was conducted by the U.S. National Library of Medicine to examine the cardiovascular risks of phentermine specifically. [24]

Here are some of the findings from the study:

Phentermine (Fastin) is approved for short-term obesity treatment in conjunction with lifestyle modifications, but is commonly used chronically.  Cardiovascular data associated with long-term use of phentermine and topiramate extended-release indicate that this combination may be a safe and effective option for reducing weight in overweight/obese patients at low-to-intermediate cardiovascular risk.

This review showed that combining low doses of phentermine and topiramate for the treatment of obesity minimized side effects while maintained weight loss efficacy. The side effects were tingling, taste changes and dry mouth.

This study brings up three important points:

  1. Phentermine was developed as a treatment for obesity, not for moderately-overweight people
  2. It was determined to be safe in a controlled setting in which low doses were administered
  3. The participants did not have any preexisting cardiovascular factors such as family history, hypertension, etc.

The health risks concern the average person wanting to lose five or ten pounds using a product made to treat obesity, with indiscriminate dosing, and without considering personal risk factors such as family medical history.

Fastin and Pregnancy

Fastin-XR also poses a specific health risk for pregnant women. Studies in animals or pregnant women have demonstrated positive evidence of fetal abnormalities. This drug should not be used in women who are or may become pregnant because the risk outweighs any possible benefit.

Fastin Drug Test

Phentermine can give a false-positive for an amphetamine. [25]. If you are subject to drug-testing, this is something you need to consider.

Fastin Drug Test
Fastin falls into the class of stimulants banned by the NCAA. If you are a college athlete, you absolutely should not take Fastin or Phentermine in an attempt to drop weight. [26]


What is the Cost of Fastin?

Approximately $19.99 for 30-ct container or $29.99 for a 45-ct container of the original formula though most retailers. Fastin also includes a money-back guarantee (MBG) if the user is dissatisfied.

A 90-ct bottle of Fastin-XR is advertised at $69.95 on the Hi-Tech Pharmaceuticals website.

Where to Buy

Where to Buy Fastin?

Fastin can be purchased at GNC, Wal-Mart, Jet.co, eSupplements.com, or almost anywhere supplements are sold. It can also be purchased directly from the Hi-Tech Pharmaceuticals website.


Fastin Directions

For those combating obesity, the directions are to ingest one capsule at approximately 2 hours after breakfast for appetite control. Late evening medication should be avoided because of the possibility of resulting insomnia.

The directions from Hi-Tech Pharmaceuticals are to take one-two tablets in the morning and 1 tablet after lunch. These directions also say not exceed four tablets daily. This comes from the 245 mg tablet bottle.

Fastin Directions
As the user acclimates to the product, the temptation may be to take more than the recommended dose. We cannot discourage this strongly enough. Fastin-XR is extremely potent, and as the dosage increases so does the potential for adverse and even dangerous side effects.

The dosing from Hi-Tech seems very high compared to the dosing suggestions that came from the doctors that formulated Fastin for obese patients. Additionally, the dosing recommendations from Hi-Tech do not account for a person’s size; it seems illogical to recommend a same dose to a 120 lb and a 320 lb person.

Fastin Diet Plan

There is not a specific diet plan associated with Fastin because it is primarily an appetite suppressant. We like safe, smart diets such as the Mediterranean Diet. You will likely cultivate your diet plan with time and experience, but we do not recommend that you use Fastin as a crutch for a diet filled with junk food.

Does It Work?

Fastin Calorie Content

No calories or carbs are found in the product.

Fastin: Does It Work?

In clinical settings, Fastin has been shown to promote rapid weight loss in obese people in conjunction with an appropriate diet. Effective findings in the non-obese population have been far less consistent.

What Users Are Saying

“I have lost 20 pounds since April and that is splurging on Friday nights (one night a week).”

“You do need to do your part though and increase your activity and decrease your junk food intake.”

“… the first time I took it, I went from a size 12 to a size 5/6. I was ecstatic. Then the formula changed and did nothing but make my heart race and feel sick.”

Also: read our Burn HD Weight-Loss Kit review »Fastin Ingredients
Bottom Line

The Bottom Line on Fastin

Fastin may be effective in clinical settings to treat obesity, but the list of side effects makes us nervous. We cannot, without hesitation, suggest Fastin as the best or safest product on the market.

If you’re researching Fastin because you want to lose weight, we understand. Our suggestion is to find one with tested ingredients and few, if any, reported side effects.

Among the best supplements we’ve found this year is Burn HD. The ingredients in are clinically-tested and safe for the general population, and best of all, the ingredients are all-natural.

Right now, you can get Burn HD as a 2-Week Sample. Try it for yourself and see.

Learn More About Burn HD »
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What are the side effects of Fastin?

Some potential side effects of Fastin are dryness of mouth, euphoria, insomnia, dizziness, restlessness, jitteriness and increased heart rate.

What are the ingredients in Fastin?

Fastin ingredients are methylphenylethylamine tartrate, methylsynephrine hcl, n-methyl-phenylethylamine hcl, synephrine hcl, theobromine anhydrous, yohimbine hcl, caffeine, dextrose, microcrystalline cellulose, hydroxypropyl methylcellulose, stearic acid, magnesium stearate, sodium starch glycolate, starch and silica.

How do I know if Fastin is right for me?

Choosing the right product is the #1 question asked by DietSpotlight readers. We recommend trying any product before buying it and know that finding a product with a sample offer is near impossible - so we created our own product, Burn HD, with scientifically backed ingredients.

Click here to get your sample of our powerful fat burner today.

Does Fastin work?

There’s no scientific research proving the effectiveness of Fastin. We found studies linking caffeine to weight-loss, but not specific to this formula.

How much does Fastin cost?

One bottle of Fastin costs $49.95. When you order two, the price increases to $95.90. Three runs $134.85. A discount is applied when you purchase more than two bottles.

How should I take Fastin?

You should take one or two Fastin capsules in the morning and another after lunch. The company suggests not exceeding the recommended serving and not taking in the evening.

Is Fastin the same as phentermine?

No, Fastin isn’t the same as phentermine. The latter is a prescription medication and the former is sold over-the-counter.

Are there any FDA advisories on Fastin?

Yes, there are FDA advisories on Fast. The agency contacted Hi-Tech Pharmaceuticals in April of 2015 about the potential dangers of r-beta-methylphenethylamine.

How much caffeine is in Fastin?

Each serving of Fastin, one capsule, contains 100mg of caffeine.

Does Fastin come with a guarantee?

There’s no mention of a guarantee with Fastin.

You might want to consider replacing Fastin with a supplement with clinically researched ingredients, like Dietspotlight Burn.

What are the side effects of Fastin diet pills?

Possible side effects to using Fastin include the following: elevated heart rate (tachycardia), an increase in blood pressure, becoming over stimulated, a feeling of restlessness, experiencing dizziness, difficulty sleeping, an unexplained feeling of euphoria, and the development of a dry mouth.

Fastin Ingredients

Fastin is a strong fat burner from Hi-Tech Pharmaceuticals. The label is clear on the official website, but you won't find amounts for most of the ingredients. A proprietary blend is used to keep details of the formula with the company.

Fastin Ingredients and Supplement Facts

Serving Size: 1 Tablet
Serving Per Container: 60
Amount per Serving% DV
Proprietary Blend with ThermoRX245mg*
- Phenylethylamine HCL**
- Methylsynephrine HCl**
- Theobromine Anhydrous**
- 1,3-Dimethylamine HCL**
- Synephrine HCL**
- N-Methyl-B-Phenylethylamine HCL**
- Yohimbine HCL**

Other Ingredients: None

We dug deep into the Fastin ingredients to give you the details you need.

Caffeine Anhydrous

Caffeine anhydrous is a dehydrated form of caffeine that’s naturally found in coffee and tea.

What is it Supposed to Do?

Because it’s a stimulant[1], it’s thought to help boost the metabolism so you can burn more fat.

Clinical Research

According to a study published in September 2007 in European Journal of Clinical Nutrition, “Only caffeine was thermogenic in the given dose and caused no haemodynamic[2] side effects.”

Theobromine Anhydrous

Theobromine anhydrous is a dehydrated form of theobromine. It is the primary alkaloid found in chocolate, and is the chemical responsible for the “feel good” reaction we get when we eat chocolate.

What is it Supposed to Do?

Theobromine is used as a stimulant, a diuretic, and a vasodialator. It is a longer acting substance than caffeine.

Clinical Research

According to a 2013 study published in Psychopharmacology, “Theobromine responses differed according to dose: it showed limited subjective effects at 250 mg and negative mood effects at higher doses. It also dose-dependently increased heart rate.”

Synephrine HCL

Also known as bitter orange, this plant has stimulant qualities that make it similar to the now banned ephedra. Because of the potential for negative side effects, the National Collegiate Athletic Association (NCAA) considers it a banned substance.

What is it Supposed to Do?

It’s supposed to boost the metabolism to make it easier to loose weight. It affects the central nervous system and may increase heart rate and blood pressure.

Clinical Research

According to a study published in a 2005 issue of The American Journal of Medicine, “Ephedra-free weight loss supplements have significant cardiovascular stimulant actions, similar to ephedra. These effects are not likely caused by C. aurantium alone.” That could mean other ingredients may be required for optimal effect.

Phenylethylamine HCL

The salt form of phenylethylamine, this chemical is used to improve mood and alertness, as well as assist with weight-loss. It is found in chocolate and is known as the “love drug.”

What is it Supposed to Do?

This chemical helps to increase dopamine levels and block the actions of dopamine receptors. Its stimulant nature makes it behave similar to amphetamines to raise the blood pressure and blood sugar levels, while also boosting metabolism.

1,3-dimethylamine HCL

This is an over-the-counter stimulant made from geranium plants.

What is it Supposed to Do?

It is supposed to help improve energy levels and promote feelings of well-being.

N-methyl-b-phenylethylamine HCL

This is another form of phenylethylamine.

What is it Supposed to Do?

Like the other form of phenylethylamine found in the formula, it is supposed to help promote feelings of well-being.

Methylsynephrine HCL

This is an ephedrine alternative.

What is it Supposed to Do?

It’s a stimulant to boost metabolism and energy levels.

Yohimbe HCL

This is a form of yohimbe that is available as prescription drug in the United States. Yohimbe is an evergreen tree found in parts of Africa.

What is it Supposed to Do?

It’s supposed to help improve sex drive and function while taking an SSRI antidepressant medication, improve athletic performance and support weight-loss.

One that we have our eye one is Dietspotlight Burn. It contains clinically-tested ingredients and supported by positive customer comments. Click above to learn more.

Fastin Scientific Abstracts

Caffeine Anhydrous

Measures of strength had been improved within all participant groups (p<0.05), while displaying no substantial time x treatment interactions. No substantial main effects or any interactions were noted for peak power. In the case of total power, a time x sprint interaction had been noted (p<0.05), without noteworthy interactions in the treatment groups. There had been an observation of a time x treatment interaction for serum creatinine values (p<0.05) that had displayed elevations in all of the groups except the placebo. 4 participants had reported minor gastrointestinal discomfort with creatine and caffeine anhydrous combination, with no adverse effects noted in any other group. The conclusion indicates that neither creatine by itself, or mixed with coffee or caffeine anhydrous had any significant impact on participant’s performance in comparison to the placebo. [1]

Theobromine Anhydrous

As expected, caffeine had an effect on the subject’s mood, alertness and cardiovascular parameters. Theobromine had differing responses according to dose, showing limited effects at 250mg and higher doses, negative mood effects. Theobromine had also dose-dependently raised heart rate. In conclusion, high doses of Theobromine were observed in humans and found that, at normal intake ranges, could lend a contribution to the positive effects of chocolate, however, at higher doses the effects turn negative. [2]

Bitter Orange

Bitter orange by itself, or within a mixture with other herbal components, had not delivered substantial adverse effects as an elevation in blood pressure or heart rate, or change electrocardiographic data, blood cell counts, serum chemistry, or urinalysis. Bitter orange by itself as well as in a mixture with additional ingredients was shown to elevate resting metabolic rate as well as energy expenditure. Also, modest raises in weight-loss had been noticed with bitter orange extract. There need to be longer term studies to further understand the efficacy of these products and to proclaim their safety under conditions such as these. [3]

Yohimbe HCL

Fat mass was substantially reduced in the yohimbine vs. placebo the assessment period following supplementation (7.1 +/- 2.2 vs. 9.2 +/- 1.9%; p < 0.05). There had been no alterations in exercise performance indicators (vertical jump, dribble and power test results, bench and leg press, shuttle run) during or between trials (p > 0.05). There had been no reports of adverse side effects from the yohimbine. Results from the study had suggested that yohimbine supplementation mixed with resistance training had not substantially changed body mass, performance indicators, or muscle mass in professional athletes. Yohimbine seems to be a useful strategy for weight-loss in athletes. [4]


Previous Fastin Review (Updated November 19, 2014):

What You Should Know about Fastin

Fastin was originally offered by prescription by the pharmaceutical company King Pharmeceuticals for Smith Kline Beecham. The company pulled the Fastin from the market in 1998, and Hi-Tech Pharmeceuticals acquired the rights to the formula and modified it to make it safe for over the counter sales. Also under this company's umbrella is the sibling supplement Fastin XR. Today, Fastin is available through the product website, although the powerful stimulant contained in the formula makes it a good idea to check with a doctor before taking this supplement. Fastin combines ingredients that will elevate the mood while stimulating the metabolism. The mood elevator makes it easier to stick with a diet and exercise program until weight loss goals are met. The powerful stimulants in the formula will offer an energy boost to help you make it through your workouts while boosting your metabolism. It should be noted that some stimulants have been pulled from the diet market because of potentially dangerous side effects that can occur. Regrettably dangerous side effects lead to litigious action as is the case with Estrin-d and Activia also. While the stimulant in Fastin is allowed in diet formulas, it is still a good idea to check with a doctor to ensure the ingredients are safe for you.


We are pleased to see that the Fastin website offers a complete ingredient list for their product. This list includes Phenylethylamine HCL, R-Beta-Methylphenylethylamine. methylphenylethylamine tartrate , methylsynephrine HCL , N-Methyl-phenylethylamine HCL, Synephrine HCL, Theobromine Anhydrous, Yohimbine HCL and caffeine. Phenylethylamine HCL is a powerful stimulant, but it is not the only one in the formula. As a side note, Triadalean is almost entirely made of phenylethylamine compounds. Dieters with heart conditions, hypertension, thyroid disorders or those on prescription medications should check with their doctor before taking this formula. It is not recommended for women who are pregnant or nursing. Those who are sensitive to caffeine may find that Fastin has undesirable side effects like jitteriness, anxiety or difficulty sleeping. The product should not be taken too close to bedtime because insomnia can occur.

Product Features

Fastin is available on a free trial through the product website. However, if you order the product and do not cancel within the first fourteen days after placing your order, you will be enrolled in the Fastin auto ship program. This means that you will receive a 60-day supply of the supplement bi-monthly and your credit card will be automatically charged. The current cost of Fastin is about $70 per month at the time of this review.

Advantages of Fastin

  • Fastin has stimulants that will speed the metabolism and boost energy.
  • The product also contains mood elevators that can help you stick with your diet program.

Disadvantages of Fastin

  • Fastin does not contain an effective appetite suppressant.
  • The formula may have undesirable side effects in some people.
  • Fastin is not safe for everyone.
  • Initial order of the product will sign customer up for auto ship program.
  • The product is rather expensive.

The Conclusion on Fastin

Fastin may help some that are extremely overweight and have not seen success with diet and exercise alone. In that respect it is similar to Optifast. However, we prefer a diet supplement that contains a safe but effective fat burner and an appetite suppressant for best results.

Article Resources
Summer Banks Dietspotlight Author
About the Author:

Summer Banks, Director of Content at Dietspotlight, has researched over 5000 weight-loss programs, pills, shakes and diet plans. Previously, she managed 15 supplement brands, worked with doctors specializing in weight loss and completed coursework in nutrition at Stanford University. full bio.

35 Fastin Reviews

  •  Bad Sideeffects
    Ben (Verified User)

    Dear Summer,

    I just took Fastin for almost 2 weeks. It worked out really well no appetite, loosing wait, feelin good… until after 8 or 9 days I felt suddenly really bad in the afternoon. It felt like I getting sick. Dizziness, headache, legs hurting a feeling of fever also. My first thought was, “damn I’ll get flued or something”. So I’ll keep on taking two pills in the morning and one after lunch but I wasnt able to work out bc of the mentioned above sideeffects of Fastin. Then last Sunday 16th of July I quit taking Fastin but the mentioned sideeffects are still. I don’t want to take everyday painkillers so, how long will those sideeffects keep on lasting and what can I do to combat them. I’ll hope to read from you asap bc at the moment I’m not able to go to work and stuff as well.

    Thanks in advance!
    Kind Regards

    • Summer (Editor)

      Hey Ben! I dug around a bit and found some information that may be helpful. According to Healthline, the effects of caffeine can last a minimum of 10 hours. That means if you take 200mg of caffeine at 3PM, by 8PM you will still have 100mg of caffeine in your system. Fastin supplies 100mg of caffeine per pill, so you are taking 200mg in the morning and another 100mg in the evening. I’m surprised you’re not having some issue with sleeping.

      Fastin doesn’t just contain caffeine, however. There are numerous stimulants in the formula and that makes the potential for side effects even stronger. Overdoing it with caffeine can lead to nausea, vomiting, dizziness and more. The effects can last days, which could be the residual you are feeling.

      Ben, I’m worried that you’re having these issues and that they’re affecting your life like this. Please keep me up-to-date on what’s happening.

      Here is a bit more research into caffeine that could be helpful: Caffeine

  • stage 4 renal failure. Is this product safe for me?

    I have stage 4 renal failure. Is this product safe for me?

  • I want to order some of the fastin diet pills
    Bernice Tweed

    I want to order some of the fastin diet pills

    • Your Name

      It causes jitters

  • Lashawn

    I’ve been taking fastin for a long time off an on an i love them i don’t have any complaints EVERYTHING AIN’T FOR EVERYBODY find something that agree with you an stop complaining about fastin i are the reason why i can’t go to GNC to purchase them

    • Silke

      Where do you get these now? GNC is a no go. Dang IT.

  • Your Namesheila

    Tell us yi was given these pills years ago from my doctor, but cant seem to get them anymore… please help me find a way to order…. no jitters, no side effects worked like a charm…. … thoughts about Fastin.

    • Your Name

      They have them at your walmart pharmacy. But because people ruin it for all of us & steal them they have to put them behind the counter. So just go ask 🙂

  • Lisaour Name

    I only take a half instead of coffee. But no one sells it at any drug stores or Gnc.Vitamin shop I’m a little upset

  •  My heart racing fast,but no energy !
    Sarah (Verified User)

    I bought mine last night otc at a local store. I read many reviews on the product. I took a half of one this am and my heart is racing no noticeable energy but I’m feeling like I’ll be thrown into a panic attack. Not suse what to think.

    • Montana (Editor)

      Hi Sarah. We suggest discontinuing use immediately. You may want to think about switching to a different weight loss supplement that is backed by science, like Dietspotlight Burn.

  • shaking so bad and jittery
    Dren (Verified User)

    I just bought a bottle this afternoon. I took one after lunch, and was shaking so bad and jittery. I haven’t been hungry or thirsty. I need to lose about 50lbs. I will try 1/2 tab in the am, a d 1/2 at lunch tomorrow. I need to motivation and energy to work out.

    • Mamie Brindley

      They do that. I love it. Wish I could afford them.

      • Montana (Editor)

        Hi Mamie! If you are looking for a more affordable way to lose weight, you may want to check out Dietspotlight Burn.

    • Youannar Name

      I just used 1 pill this morning and, I worked out 1hr. non -stop and I liked it. I weight about 156lbs and I think that tomorrow, I will take 1/2 pill because still feel jumpy… but I am still going to work outside on our yard . I use to take 1 pill of Phentermine 30 MG capsule time release,and I lost lots of weight . It was a doctor prescription and it cost my $30 for 3o pills plus doctor visit of $75 . Where FASTIN cost me 60 ct capsules $49.99 = tx

  •  Product just wasn’t for me
    jannette (Verified User)

    severe side effects similar to heart attack/stomach virus due to the vomiting

  •  Lost 40 lbs, I am happy !
    Vikki M (Verified User)

    They have totally helped me to lose 40lbs using fastin. I will continue to use them until I hit my goal which is another 20lbs. I couldn’t be happier. Thank you

  • hoping to lose weight
    michelle (Verified User)

    I’ve read a lot of good reviews on fastin. So I ordered some from the rite Aid Web site , 60 pills for 50 bucks! I can not wait to get them and along with my exercise routine, hoping to lose weight! My friend who recommended these lost 30 pounds in 2 months!

    • leah

      I started a few days ago- I can only take a 1/2 tablet or I get MAJOR jitters for the 1st 1/2 hour. What I will say is that I am eating right regardless and it does curb your appetite. I am also doing 1 hour a day at the gym, and it has made me go insanely hard at the gym (and I hate the gym). I am hoping to get rid of the 15 pounds and then discontinue and continue the gym and eating right. I have tried Phentermine before and this is working the same as a prescription. So fingers crossed with eating right- gym daily this will provide the push I needed. But the jitters are no joke!

  • I needed help
    Tammy (Verified User)

    I needed help with energy for sure but mostly was looking for a strong appetite suppressant so I’m not thinking about food 24 hours a day & eating way too much. I have found that with Fastin. Even if my stomach is growling, I don’t FEEL like eating, which is a rare thing for me. I weigh 319 right now…have only been on it for a week or so..have lost 5 lbs so far. I know this is not a long term solution. I just need a jump start to my weight loss & to be able to eat less & get used to it. The only bad side effect is that about 20 minutes after taking one pill, it accelerates your heart, which can be scary. That issue stops about 30-45 minutes after taking it & then all is good. I only take one a day (around noon) & that works for me. I don’t think my heart could deal with another pill a day.

  • Need help in choosing the best

    Hi every one,can any one help me,I checked on site for fastin,and they had a couple of different sorts.which ones are the best to take?does any one know.and I am not over weight,just midiumish want to loose about 2stones,does only over weight people take them? Or can anyone who wants to loose habit of weight can use them too?

    • edwina

      i like it . i do not get the jitters and i would start with the i like the blue white bottle that says fastin, phenylethylamine hci. i have alot of energy on these. alot.

  • I only need 30 at this time
    Mamie Brindley

    I only need 30 at this time. If they are the same as a doctor prescribed they will work. I’ve taken before they did wonders for me. If anyone has any to pitch out send them my way. They are not high priced, but they are for me.

  • help to get me back on track
    Angela Mannon (Verified User)

    I need to lose about 30 lbs. The one I have used before is now off the market. I need the extra help to get me back on track. Please email any information on this. I have heard the changed some things and it doesn’t work like it did. Can you clear that up? Thank you Angela Mannon

  •  I really like it
    Vickie (Verified User)

    I really like it . It helped me lose at and gave me engery

  •  really make one loose weigh
    charles (Verified User)

    Can you buy Fastin off the counter without a script? HOw much are they and do they really make one loose weight? I just ordered I thought it had phertermine in it and it doesn’t. I bought 6 bottles from the computer. It is like eating candy–IT HAS NO EFFECTS!!!!!!!!!!!!!!!!!!!!!!!!!!! DOes Fastin have phetermine in it? ANd where can one purchase it?

  • original formula
    April Jones

    Is Fastin- original formula still available at GNC either in stores – preferably or via to order? I was under impression it was pulled from shelves? Someone please respond via Email thank you! Love GNC 🙂

  •  Hated the product.
    Sherry (Verified User)

    This stuff does jack you up. I’m used to drinking about six diet sodas per day, but this is unbelievable (and not necessarily a good thing.) I’m shaking like a leaf and nauseated unbelievably.

  •  Loved the product.
    Alicia Smith (Verified User)

    I started taking Fastin three days ago. I have not weighed yet, but what I can tell you is I have more energy than I did and I am not very hungry. I do take it twice a day, but I do not take the recommended dosage. Right now, I am taking a half a pill around 8:30 and the other half around 12:30 or 1:00. I can tell a big difference in my appetite which is what I was looking for. It also gives me a push to work harder during my workouts. I have about 15-20 poinds left to use and I am hoping that this helps me achieve my goal. In the past, I have taken the prescription Phentermine whiuch worked for a while but the last time I got the pills it didn’t appear to have the same effect on me. So I went on a search for other supplements and I can honeslty day that this is the first one that has given me both an appetite supressant and the energy I need. If you are looking for a good product for the money…this is it!

    • Cyndy

      It has been several months since you wrote this review are you still taking the pill and if so what if any changes have you experienced.

  •  Product is not usable
    krystal (Verified User)

    i bought some from kroger and i opened iot and the pill came out like a pile of wet sand. wtf??

    • Xtiana

      The pills are highly sensitive to heat/light exposure, causing them to turn a slight brownish tinge and become VERY brittle. It does not harm the effectiveness of the drug. But if you just bought it, it was probably sitting on the shelf for some time. Just return it and attempt to get a fresher bottle.

    • Heather

      When it can out that soft thats the real fastin. Now they changed the ingredients and i dont like em…

  • Anonymous

    I found it at my grocery store, Kroger. $25 for 20 pills.