Quick Summary tl;dr
Although there are valid reasons to avoid dairy in certain cases, most people should be able to include at least small amounts in their keto diets with good results.
Indeed, studies suggest that full-fat, low-carb dairy products may promote weight loss, improve body composition, and reduce inflammation and other heart disease risk factors.
However, dairy is one of those foods that seem to affect people differently. In addition, there is a lack of research on dairy's effects in people following ketogenic diets.
Therefore, doing some n=1 experiments to see how your own body responds to various types and amounts of dairy can help you determine the best way to include it in your own diet, if at all.
Dairy has received both good and bad press over the years with respect to its effects on weight and overall health.
Although milk, ice cream and nonfat dairy products don't belong in a keto diet, butter, cheese and other types of full-fat dairy may be a good fit, depending on the individual. This article takes a look at dairy's positive and negative health effects and provides recommendations for making the healthiest keto-friendly choices if you want to include dairy in your diet.
What Are the Components of Dairy?
A dairy product is technically any food or beverage made from the milk of mammals. Although dairy from cow milk is by far the most common type consumed in the US and Europe, goat and sheep dairy products are also popular in many areas.
These are the main components of dairy:
Lactose is a disaccharide, or two-unit sugar, consisting of one molecule each of the simple sugars glucose and galactose. Enzymes in your small intestine break down lactose into these simple sugars, which are transported into your bloodstream.
Casein accounts for 80% of the total protein in dairy, including all nine essential amino acids. When milk is treated with the enzyme rennet to make cheese, the casein coagulates into curds, and the liquid portion containing whey is removed. Compared to whey and other proteins, casein takes longer to digest ( 1).
Whey protein makes up the remaining 20% of protein in milk. Most, but not all, of the whey is removed during the process of making cheese. Like casein, whey contains all the essential amino acids, although it is digested much more rapidly ( 1).
There are hundreds of different fatty acids in milk, and the great majority are saturated ( 2):
- Saturated: 70% of total dairy fat, including 11% as short-chain fatty acids like butyrate and caproic acid
- Monounsaturated: 25% of total dairy fat
- Polyunsaturated: 5% of total dairy fat, including 2.5% naturally occurring trans fatty acids. These dairy trans fats are very different from the industrial trans fats found in margarine and other processed foods. Dairy trans fatty acids seem to have neutral or potentially even beneficial effects on health, although more research is needed.
Criticisms of Dairy
Criticisms of dairy include that it is an inflammatory food, wasn't a part of our evolutionary diet, and may increase risk of cancer.
However, most of the research to date conflicts with these assertions.
1. Dairy and Inflammation
Overall, dairy products appear to have an inverse relationship with inflammation, based on the results of multiple studies ( 3, 4).
In a 2015 review of 52 clinical trials, dairy was found to have significant anti-inflammatory effects in people with metabolic disorders. In fact, the only people who showed increased markers of inflammation after dairy consumption were those with milk allergies, as would be expected ( 4).
2. Dairy and Our Evolutionary Diet
Although milk wasn't part of the diets of our earliest ancestors, there's evidence that dairy was consumed as early as 11,000 years ago in some areas of the world.
Back then, even though humans didn't produce the lactase enzyme required to digest lactose, cattle herders learned to reduce lactose by fermenting milk into cheese or yogurt. Eventually, a genetic mutation that led to lactase production spread throughout Europe, which enabled many adults to consume fluid milk without difficulty ( 5).
On the other hand, in other parts of the world where dairy wasn't consumed, people never developed the ability to produce lactase. Indeed, in some cultures up to 100% of people are lactose intolerant.
Additionally, certain evolutionary-based diets allow dairy, whereas others do not. Although a strict paleo diet excludes all dairy, primal-based diet allows full-fat, low-carb dairy products.
3. Dairy and Cancer Risk
In the past, results from observational studies raised concerns that frequent dairy consumption could increase prostate cancer risk ( 6, 7).
For instance, the 2001 Physicians Health Study of more than 20,000 men found that having more than 2.5 servings of dairy per day led to a 34% greater risk of developing prostate cancer, compared to consuming 0.5 or fewer servings per day ( 7).
On the other hand, a 2016 review found that evidence linking dairy to prostate cancer is inconsistent. Moreover, the researchers reported that dairy may actually reduce risk of colon, bladder, gastric, and breast cancer ( 8).
Overall, evidence linking dairy to prostate cancer is inconsistent and based on observational studies.
Dairy's Effects on Weight and Appetite
Many people who follow a keto lifestyle enjoy cheese, cream, butter and/or plain yogurt on a regular basis. However, others avoid it because they believe it may slow down weight loss or even cause weight gain.
Indeed, one of the arguments against consuming dairy is that its sole purpose is to help baby mammals grow.
It's certainly true that milk is a nutrient-dense, protein-rich food meant to nourish growing babies. However, there's no evidence that adults who consume other forms of dairy put on weight unless they are consuming more energy than they need.
In fact, most research suggests that dairy has favorable effects on weight loss and body composition in adults ( 9, 10, 11, 12).
In a controlled diet and exercise study of 90 overweight and obese women, the group who consumed a high-protein, high-dairy diet experienced greater loss of fat, including visceral fat, than the groups who ate less dairy and protein. In addition, the high-protein, high-dairy group put on lean muscle mass, whereas the other groups either maintained or loss muscle mass by the end of the 16-week study ( 12).
High Levels of CLA May Promote Weight Loss
One reason full-fat dairy may help improve body composition is its high concentration of conjugated linoleic acid (CLA), a polyunsaturated fatty acid that's been shown to promote fat loss in several studies ( 13).
Dairy Suppresses Appetite
Moreover, dairy may have appetite-suppressing effects. One study found that cow and especially goat dairy resulted in less hunger and increased satiety, while another reported that cottage cheese was as filling and satisfying as eggs ( 14, 15).
Dairy Can Lower Cortisol Levels and Reduce Abdominal Fat
Dairy may also help lower levels of cortisol, the stress hormone that can lead to increased abdominal fat storage when released in excess. In a controlled study, dairy helped lower cortisol levels in women on calorie-restricted diets, which may have contributed to greater weight loss ( 16).
However, some studies have shown that dairy has neutral effects on weight and appetite ( 17, 18).
Overconsumption of Dairy May Stall Your Progress
Full-fat dairy commonly eaten on a ketogenic diet is high in fat and calories and it's easy to overeat. Moderation is the key. You can find out whether you're eating too much fat by simply tracking your food.
In addition, there have been many anecdotal reports of people on keto and low-carb diets who began losing weight after cutting back on dairy or eliminating it altogether.
Dairy's Effects on Insulin Levels and Ketosis
A major criticism of dairy is that it raises insulin levels and could therefore impact ketosis. While it's true that dairy – like all protein foods – triggers the release of insulin in order to incorporate amino acids into your muscles and other tissues, its effect isn't much different compared with other proteins, at least when it comes to adults.
Back in 1997, researchers determined the extent to which a 239-calorie (1000-kj) portion of 38 foods increased insulin levels in nondiabetic individuals compared with white bread, creating an insulin index similar to the glycemic index. Cheese raised insulin more than eggs but less than beef or fish.
However, the differences in their insulin indexes were minor, especially when compared to high-carb foods ( 19):
- Eggs: 31
- Cheese: 45
- Beef: 51
- Fish: 59
- White bread: 100
- Baked Beans: 120
- Potatoes: 121
- Jelly Beans: 160
Source of graph: An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods.
Indeed, a 2016 study of 43 overweight men and women confirmed that a meat-based meal and a cheese-based meal with the same macronutrient composition had essentially the same effect on their insulin levels ( 20).
Importantly, as insulin levels rise in response to amino acids entering your bloodstream, your pancreas secretes glucagon, a hormone with effects that oppose insulin and prevent your blood sugar from dropping too low.
While dairy proteins have been found to affect insulin levels similarly to other proteins in adults, they seem to provoke a much greater insulin response in children.
For example, a 2009 study in 57 eight-year-old boys found that the whey portion of dairy raised insulin levels significantly, whereas the casein portion increased insulin-like growth factor 1 (IGF-1) levels ( 21). This makes sense, as insulin and IGF-1 demands are high in growing children.
Dairy and Cardiovascular Health
Although butter, cheese and other dairy products can raise cholesterol levels in some people, HDL values tend to increase to a greater extent than LDL ( 22). In addition, most observational studies have shown that high-fat dairy may be protective against heart disease ( 23, 24).
This includes a recent 2017 study from Iran that looked at data from 42,000 adults over an 11-year period. In this study, high intakes of full-fat yogurt and cheese decreased risk of death from heart disease by 16% and 26%, respectively ( 24).
Controlled studies have also shown beneficial effects of high-fat, low-carb dairy on heart disease risk factors.
In a controlled trial of overweight postmenopausal women, consuming 3.5 ounces (96 grams) of cheese per day for two weeks led to a 5% increase in HDL levels. In addition, the women absorbed fewer calories from fat on the high-cheese diet than when they consumed a high-meat or high-carb diet for two weeks each ( 25).
In another study of overweight adults, eating fermented full-fat dairy products – ie, cheese and yogurt – resulted in a greater reduction in inflammatory markers known to increase heart disease risk compared to low-fat versions of these dairy products ( 26).
Additionally, full-fat dairy is one of the best sources of vitamin K2 (menaquinone), which has been shown to help prevent calcium from settling in your arteries.
In the large Rotterdam study looking at dietary data from 4,000 adults over a period of 7-10 years, researchers found that those with the highest intakes of vitamin K2 had a 52% reduced risk of severe arterial calcification and a 57% lower risk of dying from heart disease (27).
Reasons to Avoid or Limit Dairy
Although eating modest amounts of high-fat, low-carb dairy may provide several health benefits, there are certain people who might be better off avoiding it or consuming it only rarely.
1. Milk Protein Allergy or Lactose Intolerance
For obvious reasons, anyone with an allergy to casein or other dairy component should avoid dairy. Some people with lactose intolerance may be able to eat cheese or yogurt; however, others may be sensitive to even the small amounts contained in these foods.
2. Hormone-Sensitive Cancers
Although some studies have linked dairy to reduced breast cancer risk, it may not be a good idea for women who already have hormone-receptive breast cancer due to its estrogen content ( 28). However, goat milk contains far less estrogen than cow milk, so including small amounts of goat cheese or yogurt may be a better choice ( 29).
Prostate cancer patients may also want to avoid or limit dairy products. A 2017 study found increased disease progression among men with recently diagnosed prostate cancer who consumed more than three servings of high-fat milk per day ( 30).
There isn't much research on dairy's effects on other types of cancer, but limiting intake to one serving or less per day may be best.
3. Individual Side Effects
Finally, if you find that avoiding dairy helps you feel better, reduces skin breakouts, decreases cravings, or makes weight loss easier, a dairy-free keto diet can be very healthy, well-balanced, and satisfying.
Best Dairy Choices on a Ketogenic Diet
Although it needn't be included at every meal, dairy can be enjoyed on a regular basis by most people. When consumed in moderation, it appears to have mainly beneficial health effects.
If you choose to include dairy in your keto diet, here are some tips for making the best choices for weight loss and overall health.
Choose Pastured, Grass-fed, or Organic Full-Fat Products Whenever Possible
In addition to having lower levels of hormones, dairy from grass-fed cows is higher in anti-inflammatory omega-3 fatty acids and conjugated linoleic acid than dairy from grain-fed cows ( 31).
Raw vs. Pasteurized
Although raw dairy has been credited with being more natural, healthier and richer in vitamins than pasteurized dairy, research suggests that they have roughly equivalent antioxidant power ( 32).
For most people, choosing raw or pasteurized dairy is a personal choice. However, for individuals undergoing cancer treatment or whose immune systems are compromised for other reasons, it's highly recommended that only pasteurized dairy be consumed from a safety standpoint.
On the other hand, those with autoimmune issues may potentially do better with raw cheese, butter or cream than pasteurized dairy products, although there is a lack of published research confirming this.
Keto-Friendly Dairy Choices
Here are the dairy choices with the fewest grams of carb per 1 ounce (28 grams):
- Butter: 0.1 gram (2 Tablespoons)
- Brie and Camembert cheese: 0.1 gram
- Muenster cheese: 0.3 gram
- Cheddar cheese: 0.4 gram
- Gouda cheese: 0.6 gram
- Mozzarella cheese: 0.6 gram
- Bleu cheese: 0.7 gram
- Cream: 0.8 gram (2 Tablespoons)
- Sour cream: 1.0 gram (2.5 Tablespoons)
- Cream cheese: 1.1 grams
- Swiss cheese: 1.5 grams
The following foods are typically consumed in larger amounts and are slightly higher in carbs. Here are the amount of carbs in 3.5 ounces (100 grams) of these full-fat dairy products:
- Plain Greek yogurt or kefir: 2-4 grams, depending how it's made (the main factor is the level of fermentation)
- Ricotta cheese: 3 grams
- Cottage cheese: 3.4 grams
- Feta cheese: 4.1 g
- Paneer: 4.1 g
Keep in mind that regardless of carb content, eating large amounts of cheese may slow down weight loss because it is high in calories, tasty and easy to overindulge in.
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