We’re hearing a lot of buzz about Muscle Milk. So, our in-depth review focused on the side effects, ingredients, customer care and scientific studies. Furthermore, we picked apart hundreds of user comments and customer feedback. Then, we summarized and refined to give you the info you need.
What is Muscle Milk?
First off, Muscle Milk is a protein powder. The ingredients are milk protein isolate, whey protein isolate, L-carnitine, L-glutamine, taurine, whey peptides, vitamins and minerals. You can use the product to replace a meal or add it to a healthy eating plan. The supplement supposedly helps build lean muscle, promotes satiety, boosts energy and aides in recovery. One benefit is that it’s available in a ready-to-go drink. 
Muscle Milk has been on the market since 2008 and is made by CytoSport. You can purchase the product at local health food stores and through trusted retailers. We like that it contains a few natural ingredients and that we located some favorable customer comments, but read on…
Unpleasant Taste – “Bleck!”
The first concern about Muscle Milk ingredients was the poor taste. “This supplement packs about 32g of protein per serving,” said our Research Editor. “But, it’s meaningless if users have difficulty drinking the first glass.” 
One customer stated, “Cannot cover up the taste of this drink. It was intolerable, undrinkable, making me nauseated upon attempting to try.”
“Taste is horrible…nothing like cake batter,” said another user.
We found in Muscle Milk reviews that taste is subjective.
“This muscle milk tasted okay as far as protein mixes go. I use it as a base for when I make shakes with fruit since it’s a pretty neutral flavor,” commented a customer.
Artificial Sweeteners in Muscle Milk – “Another Issue?”
There are quite a few complaints regarding the artificial sweeteners found in Muscle Milk ingredients. One customer said, “Too much artificial sweeteners. Can’t get past the real sweet taste.” 
Another dieter said, “Too sweet, I regret buying this.”
While some users complained about the use of artificial sweeteners in Muscle Milk, others didn’t mention it as a concern.
“It does have some artificial sweetener aftertaste, but it’s not as bad as some other brands,” said a customer.
“It’s decent. I can taste the artificial sweetener, but it’s not that bad,” reported another.
According to our extensive research, if there is a certain part of a supplement that’s concerning, like using artificial sweeteners, long-term success could be limited. If Muscle Milk ingredients are connected to a bad aftertaste, there’s an issue. 
The Science – “Any Proof?”
Muscle Milk does contain a some natural ingredients and amino acids to help build lean muscle mass. There are even studies connecting protein to satiety. Unfortunately, there’s no scientific research showing the supplement promotes weight-loss. At DietSpotlight, the review process hinges on solid science backing claims made by a company. When there’s no link to you losing weight, we become concerned. 
The Bottom Line – Does Muscle Milk Work?
So, does Muscle Milk work for weight-loss? Well, we like that it contains a few natural ingredients and that we found some favorable customer comments, but we’re concerned about this one because there’s no research showing it promotes weight-loss. Also, we’re a bit skeptical due to customer reviews talking about the poor taste, especially from the artificial sweeteners.
If you are looking to lose those extra pounds, we suggest going with a supplement containing ingredients backed by research and supported by positive customer reviews.
Among the best products we’ve seen this year is one called Dietspotlight Burn. The supplement contains four clinically-tested ingredients, which have been shown to help accelerate metabolism and jump start fat loss. People are talking about their great results and there’s no chatter about harmful side effects.
Also, the company behind Dietspotlight Burn is so confident in their supplement, they’re offering a Special Trial Offer.
Previous Muscle Milk Review (Updated February 3, 2014):
What You Should Know about Muscle Milk
Muscle Milk, created by CytoSports, is a replenishment or preparation drink for pre or post workout. Many athletes use Muscle Milk before and after events, as well. Muscle Milk is also the name for a line of products by CytoSports. The line includes shakes, bars, and oats. Muscle Milk recently revealed a light version for women and men trying to control caloric intake.
List of Muscle Milk Ingredients
Water, calcium and sodium caseinate, milk protein isolate, sunflower oil, canola oil, maltodextrin, fructose, potassium citrate, whey, natural and artificial flavor, vitamin mineral blend, cellulose gum, soy lecithin, monosodium phosphate, medium chain triglycerides, potassium chloride, sodium hexametaphosphate, acesulfame potassium, carneegnan and sucralose.
Vitamin and Mineral Blend: Vitamin A palmitate, cholecalciferol, vitamin E acetate, biotin, niacinimide, D-calcium pantothenate, thiamine mononitrate, cyanocobalamin, riboflavin, pyridoxine hydrochloride, folic acid, ascorbic acid, tricalcium phosphate, chromium chloride, copper gluconate, potassium iodide, ferric pyrophosphate, magnesium phosphate and zinc oxide. In depth information on what the effects of these ingredients can bound on the Muscle Milk Ingredients page.
The name muscle milk is a misnomer - there is no muscle support in the ingredient list unless you stretch the inclusion of sunflower and canola oil to support lean muscle mass, which is commonly claimed, but not proven. Muscle milk is a calorie replacement shake that can be used in place of other fitness shakes. The taste is what draws in many fitness people and athletes as protein powders tend to have a less than desirable taste and gritty feel in the mouth. Each Muscle Milk shake contains 25 grams of protein and only 10 grams of carbohydrate thanks to the addition of sucralose - a calorie free sweetener.
Each Muscle Milk shake is packed with tons of vitamins, including a long list of B vitamins. The trouble is, B vitamins are used by the body and then pushed out quickly. If a multi-vitamin was taken in the morning before leaving for the gym, none of the B vitamins will be used by the body before being eliminated.si
The fiber content is nearly non-existent in all Muscle Milk products. Even the oats and Muscle Milk bars contained a very small amount of fiber. Why not include a healthy ingredient like fiber when there is at least 25% of the RDA for nearly every other vitamin and nutrient?
Muscle Milk is priced about the same as other protein shakes and powders. Premixed shakes can retail for $2 or more a piece with powders priced $11, $21 and $56 depending on the size of the container.
Advantages of Muscle Milk
- All ingredients are listed online.
- High protein content should stave off hunger.
- Lower carbohydrate totals.
Disadvantages of Muscle Milk
- Low fiber content.
- Some Muscle Milk products have a lot of sugar.
- Vitamins may be pushed out of the body if Muscle Milk is consumed after taking a multi-vitamin.
For the extreme athlete, Muscle Milk could be a viable alternative, but the dieter will not find the ingredients they are searching for in the 220 calorie Muscle Milk container. Muscle Milk Side Effects could also be a potential harm to some dieters. Light and diet versions are available, but protein always carried 4 calories per gram, so more protein will equal more calories. Light and diet versions tend to have less protein and thus fewer calories.
Muscle Milk is a product from Cytosport. It is a protein supplement available in various flavors, protein amounts and delivery systems (powder, ready-to-drink). The ingredient list is rather common and doesn't show that this brand is any different from a hundred others on the market.
Muscle Milk Ingredients and Supplement Facts
Serving Per Container: Varies
|Amount per Serving||% DV|
|Milk Protein Isolate||*||*|
|Soluble Vegetable Fiber||*||*|
Other Ingredients: Canola oil, sunflower oil, magnesium phosphate, dipotassium phosphate, maltodextrin, cellulose gum, cellulose gel, medium chain triglycerides, potassium chloride, sodium hexametaphosphate, carrageenan, acesulfame potassium, potassium citrate, ascorbic acid, sodium phosphate, sucralose, vitamin A palmitate, vitamin D3
We thoroughly investigated the Muscle Milk ingredients to give you the information you need.
Milk Protein Isolate
There are dozens of protein shakes, powders and bars available to aid with fitness and weight management. One of the key ingredients in these products is milk protein isolate. While it is made from milk, the lactose is removed. However, it still provides plenty of protein and amino acids.
What is it Supposed to Do?
Milk protein isolate includes both casein and whey. After all, these are components of dairy. The purpose of this ingredient is to help build lean muscle tissue, while fueling the body and reducing appetite. It’s often consumed in powder form (added to water or milk).
Some studies have shown that lean protein is beneficial to weight-loss. For example, “Aim to get 25 to 30 percent of your calories from lean proteins, an amount shown to help maintain lean muscle and rev metabolism,” says Stuart Phillips, Ph.D., of McMaster University.
One form of protein found in numerous workout shakes and energy bars is calcium caseinate. This is a milk-based ingredient, and it’s often available in powder supplements, instant soups and coffee creamers.
What is it Supposed to Do?
Like other forms of protein, calcium caseinate is a lean source of sustained amino acids and protein. It helps fuel muscles, reduce hunger and energize the body.
There is a link between calcium caseinate and weight reduction. In fact, “Several studies support the theory that when it’s taken as part of a low-calorie diet, casein has a potential to encourage weight-loss.” In one study published in 2009 in the International Journal of Obesity, researchers demonstrated that “high-protein diets featuring casein were just as effective at producing long-term weight-loss and weight maintenance as diets featuring whey protein.”
Whey Protein Isolate
Whey protein isolate actually yields more protein than whey concentrate. After all, it is further processed in order to remove much of the fat, lactose and cholesterol. However, it still provides amino acids.
What is it Supposed to Do?
Whey protein isolate is intended to assist with muscle building and faster recovery after workouts. It is also used in many diet shakes as a lean source of protein to stave off hunger, but without causing fat gains.
According to research published in the American Journal of Human Biology in 2011, “when you lose weight, you typically lose both muscle and fat, which causes your metabolism to slow and may make it harder for you to slim down. Drinking a whey protein shake may help prevent some muscle loss, which may make it a little easier for you to continue to lose fat.”
One that’s caught our attention is called Dietspotlight Burn. It contains clinically-tested ingredients and is supported by positive customer comments. Click above to learn more.
There comes a time when a product need more attention, like Muscle Milk, so we’ll concentrate on Muscle Milk ingredients. Our attention turned to the formula, analyzing the science, benefits and negatives. Furthermore, we summarized the info to give you the bottom line.
What You Need to Know
Muscle Milk is a meal replacement shake and ready-to-drink beverage containing a protein sodium caseinate, milk and whey protein, l-glutamine, taurine, maltodextrin and medium-chain triglycerides, among others. If you use the powder, you will combine one to two scoops with water, supposedly to increase weight-loss. The suggested serving of Muscle Milk RTD is one per day. Dieters have the opportunity to use the products on the go.
The supplements, introduced as weight management aides in 2000 by CytoSport, appear to exclude artificial ingredients, a good start. Online retailers and the official website sell Muscle Milk products. We do like the length of time the company has been in business and that we found some positive customer comments, but read on…
The first concern about Muscle Milk ingredients related to stomach discomfort. “This product is a simple protein shake,” said our Research Editor. “If there are numerous reports of gastrointestinal issues, the dieter may want to take a pass.”
“Upon receiving this product and trying it for the first 2-3 times, it caused me severe GI discomfort, and I was only doing the lighter recommended serving size of 2 scoops 1-2 times daily. However, after about 10 uses, my discomfort did not subside. In fact it worsened,” said a user.
“It upsets my stomach by giving me what feels like large gas bubbles that I cannot burp up, and could potentially cause me to puke, my stomach feels very bloated,” reported a consumer.
In June of 2011, the Food and Drug Administration contacted CytoSport about Muscle Milk ingredients. Several products listed milk, although there was none found in the formula. A protein derivative is found in the product, which could be the reason it’s shown prominently.
Based upon customer comments, Muscle Milk ingredients left a bad aftertaste. “Horrible after taste on both the regular and light. Too, too sweet,” reported a dieter.
“I have been drinking Muscle Milk Vanilla for a couple of years and I can definitely…It tastes like chemicals and/or heavy metals!,” said a customer.
“Yuck. It is awful. It is gritty. It has a coconut sort of flavor. I hate it. I haven’t found any combination of other things to mix with it to make it better. Definitely not recommended,” commented a user.
After reviewing hundreds of supplements, we’ve found if any part of a product is a concern, like side effects, that could hinder long-term success. If Muscle Milk causes stomach discomfort, there’s an issue.
The official Muscle Milk website offers details about the products, but we couldn’t locate scientific research mentioning weight-loss benefits. Although several of the Muscle Milk ingredients are deemed beneficial, the American Journal of Clinical Nutrition states, “any potential benefits associated with a moderately elevated protein intake must be evaluated in the light of customary dietary practices and individual variability.” At DietSpotlight, finding science to back claims is critical. If there’s no clinical studies, we don’t spend another minute on it.
The Bottom Line
After taking a closer look at Muscle Milk, we’ve come to a decision. There are some positives, like the length of time the company has operated and that we found some favorable customer comments, but we can’t recommend it because of there’s no published clinical research supporting weight-loss claims. Plus, we’re concerned that the taste and stomach discomfort could be a problem.
If you want to drop those extra pounds, we recommend going with a product with no side effects that’s backed by published scientific research.
One of the best supplements we’ve reviewed this year is Dietspotlight Burn. The product contains a formula consisting of a four-ingredient proprietary blend, which has been shown in research to jump start metabolism and enhance fat loss. We can’t find any talk of harmful side effects and reviews on the web state dieters are seeing excellent results.
Also, the makers of Dietspotlight Burn are so confident in the formula that they’re offering a Special Trial Offer, not an every day bonus.
Muscle Milk Side Effects:
Muscle Milk, while geared to help athletes gain muscle mass, is also used by some in efforts to lose weight, ultimately burning fat by increasing muscle mass. As with any high protein muscle supplement, there are potential side-effects to consider.
Diarrhea is loose watery bowel movements that occur in conjunction with cramping and abdominal pain. It can be marked by an increased frequency of bowel movements. Cases of diarrhea can be acute, lasting from a few hours to a few days, or chronic and lasting for more than a month.
What causes diarrhea?
There are many causes of diarrhea including lactose intolerance, food allergies, food poisoning, spicy foods, and dietary changes including eating times and amounts. Taking of medications and diet supplements can cause diarrhea. More severe causes can be obstructed bowel, ulcers, and cancer anywhere in the abdominal or pelvic regions.
Abdominal pain occurs when there is an irritation or invasion of some kind in the abdomen. Most pain in this region is related to digestion in one way or another and is generally stemming from the stomach or intestines. Pain can be slight or severe, intermittent or steady. All people experience abdominal pain at one time or another.
What causes abdominal pain?
There are many potential causes of pain in the abdomen such as food poisoning, spicy foods, alcohol or taking of medications or other health supplements. More serious causes include ulcers, cancers of varying kinds, bowel obstruction, or problems with other internal organs. Abdominal pain is often associated with nausea and vomiting. 
Bloating occurs when the abdomen becomes filled with air or gas. Bloating can be uncomfortable and painful. The abdomen may appear larger than normal and may feel hard to the touch. Bloating can cause discomfort in both the abdominal and pelvic regions. 
What causes bloating?
Most likely, bloating is caused by gas, overeating, anxiety and problems in the digestive tract. In such cases, bloating should only occur for a few hours. More serious causes can include viral or bacterial gastroenteritis, an ovarian cyst, urinary tract infection, irritable bowel syndrome, Crohn’s disease, and appendicitis.
While Muscle Milk may enable the growth of muscle mass and thereby lower fat and increase metabolism, there are uncomfortable side-effects that need to be considered. As always, it is important to consult with a physician before taking any supplement.
Muscle Milk is a protein product, or meal replacement, that works to help the dieter control calorie intake and support healthy nutrition. It is a rarity to find reports of side effects, which is why so few are listed.
“I would wake up with itchy spots all over my body – on my chest, legs, butt, and arms. Everywhere.” Noah
“Upsets my stomach.” Jim
“This Muscle Milk made me so sick one evening I thought I was going to die. Two hours after making a smoothie with the chocolate flavor, I had severe stomach cramps.” Gary
“This product makes me feel sick to my stomach.” Dylan
“The high fat content of this stuff does not agree with my stomach at all, especially when I am working out.” J.D.
“There was nausea and an overall stomach soreness for the next few days.” G. Nesta
“I used to take this stuff and had bad side effects. I stopped using it. Experienced diarrhea, abdominal cramps and nausea.” Cassie
“Upsets my stomach even before I drink it.” Adriana
“I had to stop drinking it because I started having stomach problems.” Monique
“Unexplained depression, general feelings of hopelessness/flatness, fatigue and also insomnia and anger.” Chris
We know that side effects from supplements are rare, so we’re keeping an eye on one called Dietspotlight Burn. It’s not associated with adverse reactions and customers are offering positive feedback. Click above to learn more.
There comes a time when a supplement needs a little more attention, like Muscle Milk, so we’ve decided to take a close look at Muscle Milk side effects. We dug into the ingredients and clinical research. We also pored through hundreds of consumer comments and forum posts. We then condensed this info to give you the bottom line.
What You Need to Know
Muscle Milk is a protein shake containing calcium sodium caseinate, milk protein isolate, whey protein isolate, whey protein hydrolysate, whey protein concentrate, lactoferrin, l-glutamine, taurine, cane sugar, natural flavors, sunflower oil, cocoa powder, maltodextrin, canola oil and medium chain triglycerides. You can drink it in place of one or two meals a day to boost weight-loss, according to the official website. It’s a benefit that you can mix it easily.
The product, introduced as a protein supplement by CytoSport in 1999, contains some natural ingredients, a good choice. The official website and online stores sell RTD shakes and powder. We like that the company has been in business for more than 15 years and that we found some positive customer comments, but read on…
The first concern noted about Muscle Milk side effects was stomach issues. “You choose products like this as a replacement for meals,” said our Research Editor. “While this may help you lose weight, if it makes you feel sick you won’t stick with the plan.”
“I tried this milk and I have been sick over 2years now! I can’t believe it has all these terrible things in it! I can hardly eat anything because of trying this product,” commented a dieter.
“I tried MM today for the first time ever after a workout…it was pretty nasty. Plus ever since I drank it I’ve had an upset stomach,” said a user.
In June of 2011, the Food and Drug Administration contacted CytoSport because the word “milk” was used on the label, but there’s none in the product. The label still doesn’t list it, but there is protein derived from the ingredient.
Constipation – “I’m Stuck!”
Customers also reported that a Muscle Milk side effect was constipation. “Ever since I started it drinking it post work out I’ve noticed the next day I would be…Constipated,” said a customer
“I started to experience negative side effects. First off, muscle milk made me feel really constipated,” commented another
“I’ve gradually become constipated over the past week. It’s being caused by my sudden increase in milk and Muscle milk consumption. I’ve been averaging around 2-3 shakes the past few days and now I’m totally constipated,” offers a consumer.
Based on our research, if a supplement like this has even a small problem, like stomach issues, it could derail all chances of long-term success. If Muscle Milk side effects do leave dieters feeling sick, that could be enough to change their minds.
When we visited the official Muscle Milk website there was a wealth of information relating to weight-management, but the company doesn’t offer published scientific research supporting a connection with weight-loss. At DietSpotlight, a critical part of the review process is locating supporting science. If there’s none, that concerns us.
The Bottom Line
After careful consideration, we’ve come to a decision. The positives include the length of time the company has been in business and we located some favorable customer comments, but we can’t recommend it because the weight-loss claims aren’t supported by science. Plus, we’re concerned about the stomach issues and constipation associated with the product.
If you’d like to drop those extra pounds, we recommend going with a supplement that won’t cause adverse side effects, but is supported by published scientific research.
Dietspotlight Burn is one of the best supplements we’ve encountered this year. The formula contains a four-ingredient proprietary blend, which has been shown in scientific studies to ignite fat loss and accelerate metabolism. No one is talking about negative side effects and consumer comments highlight people seeing excellent results.
Also, the company responsible for Dietspotlight Burn is confident in the formula, so they’re offering a Special Trial Offer, which is a great sign.
Muscle Milk Questions & Answers:
We narrowed down hundreds of user comments about Muscle Milk into this helpful FAQ.
What are the side effects of Muscle Milk?
Muscle Milk side effects reported by users include upset stomach, nausea, irregular bowel movements, bloating and gas.
What are the ingredients in Muscle Milk?
Muscle Milk ingredients include calcium sodium caseinate, milk protein isolate, whey protein isotale, whey protein hydrolysate, whey protein concentrate, lactoferrin, l-glutamine, taurine, maltodextrin, alkalized cocoa powder, sunflower oil, corn fiber, vitamins and minerals.
Does Muscle Milk work?
We didn’t find research proving Muscle Milk works. There’s solid science linking protein to weight-loss, but nothing points toward this product.
How much does Muscle Milk cost?
The cost of Muscle Milk depends on the product you purchase. On average, the RTD beverage cost $8 and the powders run $28.
How should I take Muscle Milk?
You should take Muscle Milk according to the directions on the label. Typically, you will use one to two scoops per day or consume one RTD beverage, multiple times per day.
Can I take Muscle Milk if I have a health condition?
People taking prescription medications, anyone with health conditions, those under 18 years of age or women who are pregnant or nursing should seek the advice of a healthcare professional prior to using a weight-loss supplement of any kind, including Muscle Milk.
What do users like about Muscle Milk?
Customers reported liking the cost of Muscle Milk and the variety of flavors.
What do users NOT like about Muscle Milk?
We found some users didn’t like the taste of Muscle Milk.
How do I contact the Muscle Milk customer service department?
You can contact the Muscle Milk customer service department by calling 1-888-298-6629, using the consumer feedback form on the official website or mailing correspondence to CytoSport 4795 Industrial Way Benicia, CA 94510.
Can I contact Muscle Milk through social media?
Are there any regulatory issues with Muscle Milk?
Yes, there are regulatory issues with Muscle Milk. The parent company, CytoSport, was cited by the Food and Drug Administration in June of 2011 for mislabeling products. Supplements stated they didn’t contain milk, when in fact they did.
Is Muscle Milk lactose-free?
Muscle Milk RTD is lactose-free, but the powder contains milk ingredients.
What are the calories in Muscle Milk?
The calories in Muscle Milk vary by product. Several RTD products contain 100 calories, while the powder can contain as much as 300 calories per serving.
Does Muscle Milk come with a guarantee?
Considering Muscle Milk isn’t sold on the official website, there’s no mention of a guarantee. Contact the seller for additional details.
Do you know of any special deals or discounts on Muscle Milk?
There are deals and discounts on Muscle Milk, just not through the official website. Trusted retailers selling the supplement offer promotions.However, the last several months have been wild with our readers taking advantage of Dietspotlight Burn’s Special Trial Offer. Click above to learn more.
Muscle Milk Scientific Abstracts:
Dairy protein could indirectly enhance metabolic health (as well as a direct mechanism) by assisting weight-loss and fat mass loss via enhanced satiety. Dairy protein can accomplish this while promoting skeletal muscle growth and can act through anabolic effects of BCAAs (branched chain amino acids). These amino acids improve muscle protein synthesis, skeletal muscle metabolic function and lean body mass. The processing and the composition of dairy protein directly effects digestion, amino acid kinetics, absorption, and function. Milk possesses a way to enhance metabolic health benefits via an optimization of dairy protein composition through a combination of different components. 
Ingestion of calcium did not have an effect on 24 hour energy expenditure or fat oxidation, however fecal fat excretion did raise by -2.5 during the high calcium/normal protein diet in comparison to the low calcium/normal protein and the high calcium/high protein diets (14.2 versus 6.0 and 5.9 g per day; P<0.05). The high calcium/normal protein diet elevated fecal energy excretion in comparison to the low calcium/normal protein as well as the high calcium/high protein diets (1045 versus 684 and 668 kJ per day; P<0.05). No effects on triacylglycerol, free fatty acids, blood cholesterol, thyroid hormones, insulin, or leptin were noticed. In conclusion, a short-term elevation in dietary calcium consumption, combined with normal protein consumption, raised fecal fat as well as energy excretion by – 350 kJ per day. This conclusion could shed light on why a diet that is high in calcium could trigger weight-loss, indicating a crucial importance of dietary protein. 
A drink administered for the test containing branched chain amino acids (leucine, isoleucine and valine) resulted in substantially higher responses of insulin than the glucose reference. An additional drink made up of glucose and leucine, valine, lysine, isoleucine, and threonine copied the insulinemic and glycemic responses noticed following whey intake. With ingestion of this drink, the glucose region underneath the curve was 44% smaller (P < 0.05) and the insulin was found to be 31% bigger than that of the reference drink. Intake of the whey drink resulted in the area under the curve being 56% smaller (glucose; P < 0.05) as well as 60% bigger (insulin; P < 0.05) in comparison to the reference drink. The whey drink resulted in an 80% greater glucose-dependent insulinotrophic polypeptide response (P < 0.05). Drinks that contained free amino acids failed to affect glucose-dependent insulinotrophic polypeptide secretion. 
- 1. Milk protein for improved metabolic health: a review of the evidence (2013). Nutrition & Metabolism. .
- 2. Effect of short-term high dietary calcium intake on 24-h energy expenditure, fat oxidation, and fecal fat excretion (2005). International Journal of Obesity. .
- 3. Metabolic effects of amino acid mixtures and whey protein in healthy subjects: studies using glucose-equivalent drinks (2007). The American Journal of Clinical Nutrition. .