Milk is an incredible tool for building muscle. But why is it so good when it comes to gaining? And which type of milk is best for lean gains? For example, how does skim milk compare to whole fat milk?
Milk is designed for gains—not just getting fat
If you think about why mammals produce milk, it becomes a lot clearer why milk is such a great tool to use for getting bigger and stronger.
Female mammals produce milk to:
- make their infants grow big and strong. It is full of nutrition, with protein, carbs, and fats. There are salts, minerals, and vitamins (vitamin a, b, d, k—for example).
- give their infants something safe to drink while they’re small. There are no toxins in milk, and it will be safe to drink even when clean water is not guaranteed).
- give their infants an immune boost with protective compounds. Milk will contain immune-boosting, stress-beating, and antioxidant compounds (study, study, study). For example, in cow milk, there is a compound called CLA that helps to fight cancer. You might know CLA as a supplement people take for its fat-burning and fat prevention effects.
- give their infants something incredibly easy to digest for rapid and efficient growth. Milk is known as the highest-scoring protein in quality (digestability and amino acid scores.)
So when you think about it, milk is designed for healthy and fast growth. It isn’t designed to make you bigger by storing fat—but rather through lean gains.
But is cow milk healthy for humans to drink?
But cow milk is made for baby calves, not humans. Is it healthy for us to drink it?
(We’re focusing on cow milk because, in developed countries like ours, cow milk makes up 98.1% of all milk, though goat, sheep, and buffalo are excellent choices as well.) (UN FAO)
A 2016 meta-analysis titled “Milk and dairy products: Good or bad for human health? An assessment of the totality of scientific evidence” gives us a clear answer. Researchers found that having milk and dairy:
- milk and dairy help people have a healthy bodyfat level and muscular strength. Being overweight, obese, or weak will also have associated health risks, especially in today’s obesity epidemic, so milk can help on this front.
- milk and dairy reduce the risk of cardiovascular disease. And an even more recent review from 2019 on milk and cardiovascular disease found the data saying the same thing. Both whole-fat and non-fat dairy was found not to harm cardio health. (2019 review)
- milk and dairy have a neutral to reduced risk with type 2 diabetes.
- milk and dairy can help improve bone mineral density. (The data says it’s not clear if milk reduces bone fractures though. If I were to guess, this is because cow milk can’t solve our bone density problem on its own. Perhaps we’re still on the hook for reasonable sun exposure to help move calcium out of the gut and into the right places in the body. (study)
- milk and dairy could lower the chance of certain cancers. Colorectal, bladder, gastric, and breast cancer had their risk lowered.
- milk and dairy have an inconsistent relationship with prostate cancer across studies (some good, some bad). Dr. Brad Dieter writes that even in those studies linking milk to prostate cancer, the risk is still incredibly low. If prostate cancer is a worry, I’d personally focus on getting reasonable, daily sun exposure, and making other improvements to my lifestyle. (study, study, study, study)
- milk and dairy were not associated with all-cause mortality.
After reviewing all the evidence, researchers found that milk:
- is nutritious
- helps people to stay lean and strong
- protects against some diseases and cancers
- and has very few downsides (if at all)
All milk is healthy—but A2 milk might help those can’t have milk
There is a debate right now, with the research still inconclusive, comparing A1 milk to A2 milk. Some cows have the genetics of A1A1 (outputs A1 milk), A1A2 (outputs a mix), and A2A2 (outputs A2 milk). As a herd, all their milk will get mixed, so all cow milk will have some of the A1 beta-casein protein. The argument is that A2 milk is even healthier than A1 (and could even be causing the lactose intolerance problem we see today.)
Goat, buffalo, and human breastmilk are all A2. So if you know someone who can’t have cow cheese, but can have goat cheese, it may not be the lactose but rather the A1/A2 protein difference.
But the research is too early to tell if A2 is indeed better than A1 milk. But if you or someone you love struggles with “lactose intolerance,” you may want to read our section on A1 vs. A2 milk here.
How does milk help build muscle?
- Milk has a lot of protein per serving. Each cup (250ml) of milk has nearly 9 grams of protein.
- Milk is made up of a blend of whey (20%), and casein (80%). And whey is the most studied and best performing muscle-building supplement there is.
- Milk might help to build more muscle by covering both short and long protein absorption speeds. Milk contains both whey, which is absorbed fast, and casein, which is absorbed slowly. Milk has both and could lengthen the process of muscle protein synthesis compared to either just having whey or casein. (study)
- Milk is the top-scoring protein quality. That means it’s the most easily digested protein we know of.
- Milk has 18 amino acids, including all nine essential amino acids. Milk also includes high-amounts of leucine (0.3 grams per 100g of whole milk). Leucine is the key amino acid thought to help activate muscle protein synthesis, the process of sending protein to your muscle tissues to build them up. (USDA Nutrient Database)
- Milk helps to keep you hydrated and may even speed up recovery while reducing soreness. In a 2019 review, researchers found that some studies showed that milk helped with performance and recovery (but some studies showed no effect). So milk might help with keeping our maximal effort high as the workout continues, and reducing post-exercise soreness and tiredness (in both men and women.)
Whole fat milk is even more powerful for building muscle
In the fat of milk, there are approximately 400 different types of fatty acids (article). When you remove these fatty acids, you’re removing the natural synergy of the makeup of milk.
In a 2006 study, researchers had men do ten sets of a knee extension exercise, and then they were split into groups that had:
- fat-free milk: 56 calories, 8.8 grams of protein
- whole fat milk: 150 calories, 8.0 grams of protein
- matching-calorie-fat-free milk (with more protein): 150 calories, 14.5 grams of protein
The researchers were shocked when the whole-fat milk group got more gains because it had less protein in it. They had thought the third option with nearly double the amount of protein would have performed the best. The researchers wrote:
“These data suggest that some property of [whole milk] enhanced the amount of threonine, and possibly phenylalanine, utilized for muscle protein synthesis. If true, it is not clear which property of [whole milk] was responsible for increased utilization.”
When you remove the fat, you are playing with the natural makeup that researchers know little about.
Bulking? Whole milk could also prevent fat-gain and make gains leaner
Paradoxically, getting more fat, more calories, and less protein, with whole milk, may help to keep your gains even leaner.
This is because whole milk doesn’t just have muscle-building advantages in the fat of milk, there are also fat-burning compounds in the milk fat. For example, there is something called conjugated linoleic acid (CLA) that is in the fat. CLA has been found to fight against fat gain, promotes burning fat, and helps with heart health (review). Not only that, but CLA has been found to fight cancer, diabetes, obesity, and fatty plaques in the arteries that cause (that’s how it helps with heart health). (paper)
(Want to maximize your CLA intake from milk? Get organic or 100% pasture-fed whole milk. Cows that feed on pasture, even just for 1/3 of the time as required with organic milk, they’ll output much higher levels of CLA (and omega-3s) in their milk.)
Here is some research detailing more about whole milk helps to keep body fat in check, even though it has more calories and less protein:
- In a meta-analysis on high-fat dairy, researchers found that having full-fat dairy was associated with a lower risk of becoming obese.
- In this study on men aged 40-60 years old, those who ate butter, full-fat milk, and cream had less of a gut. (study)
- In a study of nearly 20,000 women over nine years, the women who consistently had whole fat milk and cheese had an inverted relationship with weight gain. Meaning that they didn’t get fatter over the nine years, while those who drank no milk or low-fat milk didn’t get those same benefits.
- In these three studies (study, study study), having full-fat milk was associated with having a lower risk of metabolic syndrome, and a lower risk of diabetes.
Is there something unique going on with the whole fat milk that is making it better for building muscle, better for preventing fat gain, and better for health?
Perhaps maintaining the balance and synergy of the 400 fatty acids found in the milk fat are causing these outcomes.
A small note on homogenized milk
I personally don’t buy homogenized milk anymore. It is a mechanical process that puts the milk through a high-pressure machine. Homogenization breaks the fat globules down, so they’re much smaller than they were originally. The smaller fats stay mixed and will not separate into a cream and milk layer. Plus, dairy manufacturers will then skim out some of the fat, even in whole milk, to standardize it. I’ve been drinking non-homogenized milk to minimize processing, to get the full fat-value with no standardization, and I find that it tastes smoother.
Organic and pasture-raised cows for better gains, fat-burning properties, and health
In this study, researchers wrote:
“The output of vitamins in milk was within farm positively correlated to supply of vitamins from roughage.”
In other words, the milk can only be as good as what the cow eats.
In a 1999 study, cows were fed different diets like corn silage, alfalfa hay, and going out to pasture.
Researchers found the cows that were 100% pasture-raised had 500% higher levels of CLA compared to a conventional diet. They found 22mg of CLA per gram of milk compared to only 3.9mg per gram of milk.
- Linolenic acid up by 60%
- eicosapentaenoic acid (EPA)up by 32%
- docosapentaenoic acid (DPA) up by 19%.
In a 2007 study, researchers found you could even see the difference with pasture-fed cows. The milk becomes more visually yellow because there are higher levels of beta-carotene, lutein, vitamin E, and sesquiterpenes.
Many vitamins, like vitamin A, D, and K, are “fat-soluble” and are only found in the fat. When you remove the fat, you are removing the vitamins (and so skim milk is fortified later during the homogenization process.)
But isn’t all that saturated and trans-fats bad for your health?
The main reason I hear when people tell me why they drink skim milk is because it’s better for their health.
Let’s first look at the research on dairy trans-fat.
Trans-fats in milk—is it bad for us?
Trans-fats can occur naturally in cows milk (and human breastmilk), and they can be industrially produced. In industrial cooking, they process an oil so that it becomes solid at room temperature, and it can help extend the shelf life of products.
Trans- is just the configuration of the acids. And all the research so far on trans-fat being so bad for our heart health has been on industrially produced fats—not the ones occurring naturally.
From a 2015 review on saturated fat and trans fat on cardiovascular health and mortality:
“The major industrially produced trans fatty acids in the food supply are elaidic acid isomers, and the major [mammal] derived trans fatty acid is vaccenic acid; both share the characteristic of having at least one double bond in the “trans-” rather than “cis-” configuration.”
So, the trans-fats in cows milk (and breast milk) are different acids than the trans-fat we used to find in those dusty-year-old cookies at the convenience store.
Plus, it seems like our body knows what to do with this trans- “vaccenic acid.” Our body converts it into conjugated linoleic acid—CLA. Yeah, that’s the same anti-cancer, fat-burning, anti-inflammation compound that continues to show up. So, it seems like the trans-fats from milk isn’t that bad for us compared to industrial trans-fats, and it may even be good for us. (study, study)
In that 2015 review we brought up earlier, the researcher wrote that even if the natural trans-fat in dairy is found through new research that it *is* bad for our health, it won’t matter. The trans-fat that are in milk are in such small levels compared to how high they are in the industrially produced foods that we know are bad for us.
Saturated fat in milk—bad for cardiovascular health?
The fat in milk contains dietary cholesterol and saturated fat—this is what scares people. To be clear, dietary cholesterol and saturated fats will also help them to build muscle and to maintain healthy testosterone levels. (study, study)
Consuming too many saturated fats is commonly believed to cause “bad” cholesterol levels, and then that would cause heart disease.
So, it would follow that the way to beat this is to remove all the fat from milk and drink skim milk.
But does high LDL cholesterol levels actually cause heart disease?
In a 2016 review of all the research, researchers wrote:
“The cholesterol hypothesis predicts that LDL-C will be associated with increased all-cause and [cardiovascular] mortality. Our review has shown either a lack of an association or an inverse association between LDL-C and both all-cause and [cardiovascular] mortality.”
“Our review provides the basis for more research about the cause of atherosclerosis and [cardiovascular disease] and also for a re-evaluation of the guidelines for cardiovascular prevention, in particular, because the benefits from statin treatment have been exaggerated.”
In 2017 an evidence-based editorial was published in the British Journal of Sports Medicine titled: “Saturated fat does not clog the arteries: coronary heart disease is a chronic inflammatory condition, the risk of which can be effectively reduced from healthy lifestyle interventions.” It was authored by 11 experts, and covered a large meta-analysis that found that saturated fat isn’t associated with cardiovascular disease.
The authors wrote that the main problem of atherothrombosis could be fixed by walking at least 150 minutes a week. To fight cardiovascular disease, we should shift the message to walk 22 minutes a day and eat real food.
And in a published 2018 review titled “Dairy Fats and Cardiovascular Disease: Do We Really Need to Be Concerned?” the authors write:
“Previous research indicated that reducing serum cholesterol levels would lower cardiovascular risk, however, [cardiovascular disease] are a multifaceted disease, which requires a multifaceted approach to primary prevention.”
“Despite the previous concerns about dairy product consumption due to the [saturated fatty acids] content, it has been shown that not all [saturated fatty acids] are created equal and that the presence of specific fatty acids (C14:0,C15:0, C17:0, CLA and trans-palmitoleic) in circulation are associated with a lower incidence of several cardiometabolic disease…”
“Several meta-analyses point to the resounding conclusion that, although dairy products contain a high [saturated fatty acids] content, their consumption induces a positive or neutral effect on human cardiovascular health (study, study, study)”
So it’s possible that dairy saturated fatty acids are different than other types of saturated fatty acids.
(This reminds me, organic and pasture-raised milk improves the ratio of the fats by having more omega-3s.)
I can think of a couple of people who are drinking skim milk for their heart health. But they’re also occasionally eating processed foods like hot dogs, cold cuts, fried foods with palm oil, etc. My suggestion would be to switch to whole-fat milk for all the muscle, fat-burning, and health benefits. Then go for a walk every day outside in the sun. And cut it out with the hot dogs and processed foods with high-saturated fats.
If you want to learn more about the research on milk and health, check out our full super-guide on milk here.
- A 2016 meta-analysis on dairy and health found that milk is:
- good for managing body fat and strength
- reduces the risk of cardiovascular disease
- improves bone mineral density
- lowers the risk of certain cancers
- is not associated with all-cause mortality (few downsides, if any at all)
- Those who can’t drink milk may want to investigate A2 milk (goat, buffalo, and specific branded cow milk)
- Milk helps to build muscle by:
- having a lot of protein per serving
- having a blend of both fast (whey) and slow (casein) types of protein
- being the top-scoring protein studied
- having 18 amino acids and with high levels of leucine (which helps activate muscle protein synthesis)
- helps our bodies stay hydrated and possibly reduce soreness, for better training
- Whole fat milk contains approximately 400 different types of fatty acids
- Whole fat outperforms skim and low-fat milk when it comes to
- building muscle
- staying lean and burning fat
- Organic milk (at least 1/3 of the year must be in the pasture) improves the fatty-acid composition in milk, such as having higher levels of CLA and omega-3s compared to conventional milk
- 100% pasture-raised cows produce the best milk with more nutrients due to their superior diet
- Dairy trans-fats aren’t the same as industrial trans-fats, and don’t seem to be bad for our health, and are possibly even *good* for our health
- A 2016 review, a 2017 editorial, and a 2018 review seem to cast doubt on saturated fats causing heart disease, and dairy saturated fats in particular. Instead of drinking skim milk, perhaps we should be walking at least 22 minutes a day, and eating more unprocessed foods.