Two containers of yogurt sit side by side, one fat-free and one full-fat. Now, without any other information about the contents therein, answer quickly: Which of these has been scientifically proven to cause weight gain and heart disease, and which has been proven to support weight loss and coronary health?
If you’re like most people who pay even modest attention to prevalent nutritional news bites, you’ll crown the low-fat stuff as the healthier choice. And despite the fact that your answer would be solidly backed by majority opinion, you’d be wrong.
The correct answer to both questions is actually “neither,” since researchers have yet to provide concrete support for the much-ballyhooed reputation of low-fat dairy products as a heart-healthy, weight-loss panacea. Nor have they confirmed the reputation of full-fat dairy as a diabolical threat to coronary health and waistline reduction.
That comes as a shock to a lot of folks, including health professionals. “Probably most people who think of themselves as nutrition-savvy would be astonished to learn that evidence of whole milk’s being a ticket to an early grave is conspicuous by its absence,” says food historian Anne Mendelson in Milk: The Surprising Story of Milk Through the Ages.
The prevailing understanding of low-fat dairy products seems to owe more to powerful food-industry campaigns and wishful thinking than to convincing scientific data.
In 2003 the National Dairy Council began aggressively promoting the claim that consuming three servings of low-fat dairy products daily would contribute to weight loss, deploying photographs of slender celebs like David Beckham and Kate Moss in milk moustaches to drive its message home.
Not surprisingly, this message was quickly co-opted by several large manufacturers of cheese and yogurt, and soon the idea that low-fat dairy could aid weight loss seemed like established fact.
Of course, just saying it does doesn’t make it so, and in this case the Dairy Council seems to have been bending the truth.
The weight-loss portion of the council’s three-a-day campaign was halted in 2007, after a lawsuit by the Washington, D.C.–based Physicians Concerned with Responsible Medicine charged that 24 of the 27 research studies behind the claim had not only failed to prove a connection between dairy and weight loss, but they had all been directed by a single researcher and funded by the Dairy Council.
The Federal Trade Commission ruled that the ads were misleading, and the Dairy Council was forced to pull them.
While there have been a number of studies showing a correlation between low-fat dairy consumption and weight loss, skeptics argue that this is very different from showing causation, since in most cases the dairy that subjects consumed was likely replacing other less wholesome foods, as with one study in which teenage skim-milk drinkers showed a weight-loss advantage over their soda-drinking peers.
While there have been a number of studies showing a correlation between low-fat dairy consumption and weight loss, skeptics argue that this is very different from showing causation, since in most cases the dairy that subjects consumed was likely replacing other less wholesome foods, as with one study in which teenage skim-milk drinkers showed a weight-loss advantage over their soda-drinking peers. The problem is that there’s no way of knowing if having the teens replace soda with whole milk might have delivered the same results, and no reason to think that replacing the soda with, say, tomato juice or water might not have had an even more advantageous effect.
Still, Kate Moss in a milk moustache seems to have made a much more lasting impression than the physicians’ lawsuit, and it remains a widely held belief among health professionals and average eaters alike that fat will make you fat and low- to no-fat foods, especially low-fat dairy products, will make you look more like David Beckham.
Beckham’s abs notwithstanding, the popular reception of the campaign connecting low-fat dairy to weight loss was likely compounded by the longstanding popularity of the “lipid hypothesis.” This is the theory — a theory never proven to many experts’ satisfaction — that saturated fats cause heart disease and obesity. Despite a lack of scientific support, the hypothesis has been promoted unquestioningly by most nutrition scientists and government officials since it was first proposed in the 1950s.
In 1977, a Senate committee even published a low-fat manifesto entitled “Dietary Goals for the United States” that marked the start of a veritable industrial-food revolution that allowed manufacturers to promote margarine and corn syrup as health foods: Look Ma, no saturated fat! As the theory gained traction, full-fat dairy products fell out of favor and even became reviled by many well-intended dietitians. Meanwhile, low-fat dairy products did more than just survive the trend — they thrived.
Today, Americans buy about two-and-a-half times more skim milk each year — and about half as much whole milk — than they did in 1975. This would likely shock earlier generations of dairy farmers who prized the richness of whole milk and cream and often threw the skim to the hogs.
Today, whole milk has become a relative rarity. In 2008, Starbucks switched its standard milk from whole to 2 percent, all in a bid to adopt a healthier profile in accordance with low-fat doctrine.
But here’s the disconnect: During the same period that the consumption of low-fat fare rose in the United States, our rates of obesity, type 2 diabetes and heart disease multiplied exponentially — a fact that many health experts attribute to our replacing natural whole foods rich in nutrients (including naturally occurring fats) with nutrient-poor, processed foods dense in sugar, refined carbs and commercial oils.
Both this trend and a number of recent studies are suggesting that fats from whole foods — even the saturated kind — are not the enemy we’ve been led to believe. Which means that low-fat dairy may not be nearly the nutritional and weight-loss ally it once seemed.
A Second Look at Saturated Fats
A 2001 study by nutrition scientists at Harvard School of Public Health and published in the Journal of the American College of Nutrition reveals that the lipid hypothesis is supported by only two research experiments — while a great many more studies have failed to find a positive correlation between saturated fat and heart disease. That’s not a very strong foundation for what has essentially become nutritional gospel.
Critics like Mary Enig, PhD, an expert in lipid biochemistry and author of Know Your Fats (Bethesda, 2000), have long insisted that evidence tying dietary fat and cholesterol to blood cholesterol and arterial damage is likewise suspect. They suggest that because the body produces cholesterol to heal internal injuries, elevated cholesterol levels could just as well be a response to coronary damage as a cause of it. (For more on the cholesterol controversy, see “Cholesterol Reconsidered” in the June 2009 archives.)
Enig points out, moreover, that a low-fat dietary approach can have a number of negative health effects, some of which are tied to reduced absorption of certain nutrients that can only be assimilated in the body when accompanied by appropriate fats.
“Most people are at risk for lowered intakes of the important fat-soluble vitamins and other fat-soluble nutrients when they consume low-fat diets for any length of time,” she says.
“Most people are at risk for lowered intakes of the important fat-soluble vitamins and other fat-soluble nutrients when they consume low-fat diets for any length of time.”
Likewise, the Harvard study goes on to state that the popularization of a low-fat diet may have caused “unintended health consequences” by encouraging increased general consumption of refined carbohydrates and trans fats. The bad press about naturally occurring saturated fats played a key role, for example, in driving people to embrace processed-food products like powdered coffee creamers, fake whipped-cream products and margarines.
Both trans fats and carbohydrates of any kind were once praised as healthful replacements for traditional foods containing saturated fats, but recent studies have shown them to be more likely accomplices to skyrocketing obesity, diabetes and heart-disease rates.
David Ludwig, MD, PhD, an endocrinologist at Harvard who heads the renowned OWL Program (Optimal Weight for Life) for childhood obesity at Boston University Hospital, has had real success using a low-glycemic approach to weight loss rather than a low-fat one.
In Ludwig’s view, the insulin spikes and hunger crashes caused by high-glycemic foods are far more likely to spur weight gain than a reasonable intake of unrefined saturated fats, including those in full-fat dairy products, which help moderate appetite naturally.
On this basis, he explains, no- or low-fat dairy may actually function as an obstacle to weight loss for some people. When the fat is removed from milk, what remains are a significant number of unabsorbable fat-soluble vitamins and an overabundance of lactose, or milk sugar, with some protein but no fat to slow its entrance into the bloodstream. This doesn’t even account for the copious amounts of sugar often added to low- and no-fat dairy products to improve their taste in the absence of naturally pleasing milk fat.
It’s also likely that one will drink much more skim milk than whole (or eat more low-fat yogurt, fat-free sour cream, low-fat ice cream, etc.) for three reasons:
- It generally takes larger servings of low-fat foods than full-fat foods to switch on our bodies’ satiety signals.
- There’s a psychological tendency to feel that because we’re “being good” by eating these low-calorie, low-fat products, we are justified in “making up for it” by eating more of them — or more of something else.
- Low-fat foods don’t keep us satisfied for as long and may also destabilize blood sugar, so we’re likely to experience cravings to want to eat again sooner.
This last point deserves some explanation: Low- and no-fat dairy delivers more fast-absorbing lactose to the bloodstream, and more potential for corresponding insulin spikes and resultant sugar cravings. Full-fat dairy doesn’t have this effect. “The proportion of lactose decreases with every increase in milk-fat content,” Mendelson explains. So relative to skim milk, “heavy cream contains only minute amounts.”
Finally, not only does an extra dose of lactose potentially lead to insulin problems, many experts argue that most of us aren’t genetically inclined to digest it well in the first place.
According to Mendelson, about 70 percent of us are at least somewhat dairy intolerant as adults. In fact, we stop producing lactase — the enzyme that breaks down lactose in the intestines — shortly after we’re weaned, when we technically no longer need it. Eating dairy may not make us immediately ill, but undigested lactose in the intestine can cause all kinds of unpleasant symptoms, from painful bloating, flatulence, diarrhea and stomach cramps to skin rashes, acne and ear aches.
Most dairy-eating cultures have historically consumed milk in its fermented or soured state, from the yogurt of the Middle East to the clabbered milk of the American South.
Mendelson notes that most dairy-eating cultures have historically consumed milk in its fermented or soured state, from the yogurt of the Middle East to the clabbered milk of the American South. This may have been because dairying has been around a lot longer than refrigeration, and fermentation functions as a preservative. But fermentation also promotes digestibility by effectively “predigesting” the lactose before it can cause trouble in the intestines.
Even so, says Mendelson, the idea of milk as a core nutritional staple is foreign to most dairying cultures, where they tend to consume even soured milk products sparingly, not in tall frothing glasses several times a day. Including moderate amounts of dairy products can work well for those who enjoy it and tolerate it well, she notes, but depending on dairy as a primary source of nutrition is probably unwise for most of us. And for those who don’t tolerate dairy well, there’s no reason to be concerned about lack of dairy leading to nutritional deficiencies. “Anyone can happily live without using milk in any form,” says Mendelson, an idea that can be hard for what she calls our “milk-in-every-fridge” mindset to grasp.
In Fat’s Favor
So, low-fat dairy may not be all it’s cracked up to be, and perhaps dairy in general has been oversold as a health food. Still, a life without any dairy might seem like just a little too much self-denial. If you’re not lactose intolerant, and you’d like to enjoy healthier dairy when you do consume it, here’s what some of the research suggests about why old-school full-fat dairy products might be worth embracing:
Ludwig favors the consumption of some unrefined fats for kids trying to lose weight, since fats actively promote a stable metabolism. Fat is digested slowly, which helps decrease the rate at which carbohydrates are released into the system. This in turn makes the body more receptive to a pancreatic hormone called glucagon that “unlocks” fat stores for energy. If there’s too much insulin from eating high-glycemic foods (like heavily sweetened fat-free yogurt), the body decreases or stops glucagon production, which stalls fat burning. Fat is also the nutrient that triggers the brain to recognize satiety, which offsets overeating.
In contrast with its fortification requirements for 2 percent, 1 percent and skim milk, the federal government doesn’t require whole milk be fortified with vitamin A. That’s because about 1,400 to 1,600 International Units (I.U.) are already in the milk fat. Skim milk does have a slightly higher percentage of vitamins D, E and K than whole milk, but it probably doesn’t serve much purpose: All these vitamins are fat-soluble, so without fat, they pass out of the small intestine undigested.
Sex Drive and Fertility
The very chemicals that make us able to reproduce our species — testosterone, estrogen and progesterone, among others — are synthesized from the cholesterol produced by our bodies and found in dietary sources such as milk and other animal fats. That’s why fibrates and statins, medications used to lower cholesterol levels, can also markedly decrease sex drive. Eating full-fat dairy might also help women get pregnant, at least according to a 2007 study at the Harvard School of Public Health that found women who consumed at least one serving a day of full-fat dairy were 27 percent less likely to experience ovulation-related fertility problems.
Milk fat contains glycosphingolipids, which some studies have shown to have infection- and disease-fighting properties. “Butterfat is an amazing fat — it has properties that support gut flora; it has properties that support your immune system; it has properties that fight cancer,” says Sally Fallon, coauthor of Eat Fat, Lose Fat and founder of the Weston A. Price Foundation in Washington, D.C., which promotes traditional foods and farming methods. “Vegetable oil doesn’t have those things.”
A Healthy Balance
So is there a place for full-fat dairy in your diet, or not? That all depends on you — how much you like dairy, how well you tolerate it, and what impact it seems to have on your personal biochemistry and metabolism. All these things are highly individualized. The important thing is to acknowledge both dairy’s strengths and its potential drawbacks.
Mendelson stresses the fact that many of our problems with milk began when we started asking it to be “nature’s most perfect food,” expecting it to cure everything from gout to malnutrition to obesity. This was asking too much. “No food has to pretend to be all things to all people,” she says. Meanwhile, as the premium placed on daily fresh-milk consumption in the United States clashed with the lipid hypothesis, many of the things that were originally healthy about dairy got lost in the skimming and processing anyway — even as we consumed more of the stuff than ever.
Thankfully, there seems to be a middle way. In the light of more moderate expectations, it does seem that many of us can enjoy some benefits and pleasures from full-fat dairy products as part of a diet based on a variety of synergistic whole foods. Ultimately, each of us needs to decide which dairy products, if any, feel best for us. “If we can shed the notion that chugging down so much milk a day is a duty,” Mendelson offers, “perhaps we will be free to discover different forms of it as a joy.” And if we can get over our notions that low-fat dairy is the only kind worth eating, our guilt-free enjoyment of full-fat yogurt, cheese, butter and cream may increase that much more.
In contrast to the slew of “does a body good” messages generated by the American Dairy Council, milk is really only digestible by a small population of people who have “lactase persistence,” a condition that allows them to comfortably break down lactose throughout their adult lives. For everyone else it can pose significant digestive challenges. Most of us are better off with soured dairy products like cheese or yogurt, which are produced with a fermentation process that “predigests” the lactose.
For those who don’t tolerate any dairy well, milk substitutes can be a welcome treat. Sheila Dean, a Palm Harbor, Fla.–based nutritionist, treats many dairy-sensitive people in her practice. She’s happy to recommend milk substitutes as long as people don’t go overboard with them. “Most milk substitutes do have quite a bit of sugar, so as with anything, the key is moderation,” she says.
Rice Milk: Though rice milk is highest in sugary carbohydrates, it’s the milk substitute that Dean recommends most often to her allergy-prone clients. “Some people who have problems with milk also have issues with soy and nuts, and rice milk is really benign,” she says.
Soymilk: Soymilk is high in fiber and contains plenty of protein. It has a fuller flavor than rice milk, and the better brands can hold their own in tea or coffee. It does have its detractors, though. Ron Schmid, ND, author of The Untold Story of Milk, believes that because the soy in soymilk has not been fermented (like miso, tofu and other traditional Asian soy foods), there’s a risk that soy estrogens will depress thyroid function.
Hemp Milk: Hemp milk seems likely to emerge as a real winner in the competition between milk substitutes. It has a growing legion of fans — both for its flavor and texture (smooth, rich, plenty of body) and for its impressive nutritional profile: One cup contains 46 percent of your daily calcium requirement, along with a wealth of other vitamins, minerals, and essential omega-3 and -6 fatty acids.
Goat’s Milk: Though technically a dairy product, goat’s milk is more easily digested by many people who are sensitive to cow’s milk. Swiss naturopath and allergy specialist Dr. Thomas Rau recommends it for his patients because the casein “curd” is softer and more digestible than the curd in cow’s milk. It’s also a whole, unprocessed food.
Doing Dairy Right
If you’re aiming to improve the overall quality of your dairy choices, look for the following labels:
“Pasture-Fed” or “Grass-Fed”
Milk from pasture-fed cows has significantly more omega-3 fatty acids, according to a 2008 study by the Nafferton Ecological Farming Group at Newcastle University. It also contains a dietary compound called conjugated linoleic acid (CLA), shown to help reduce body fat and increase lean tissue. The key to the production of CLA appears to be in the fresh grass cows eat, so grain-fed dairy products won’t have the same benefits. Pasture feeding is also the most humane method of keeping livestock, and the low-stress conditions keep stress hormones like cortisol and adrenaline out of the cow’s milk.
USDA Organic guarantees that cows are getting organic-certified feed and aren’t given antibiotics or bovine growth hormone (rBGH), which means the milk has fewer toxic byproducts. This is particularly important for full-fat dairy, since toxins concentrate in animal fat. A note of caution, however: Organic is often assumed to indicate better living conditions for the animals, but Anne Mendelson, author of Milk: The Surprising Story of Milk Through the Ages, is skeptical: “There are huge organic dairies out West where the cows are treated just as badly as on any factory farm.” She sticks with dairy from small, local producers whether or not they’re designated organic. Learn the names and brands of your nearest grass-fed milk producers at www.eatwild.com.
Homogenizing milk has little to do with milk safety (pasteurization is what kills bacteria); it’s a cosmetic process that prevents the cream from rising to the top. Fat globules are extracted and treated with high pressure to destroy their original membrane and reduce them to a uniformly smaller size, then injected back into the milk at artificial ratios. Fresh, unprocessed milk ranges from 4 percent to 5.5 percent milk fat versus only 3.25 percent for homogenized whole milk. This can undermine the nutritional benefits in the milk fat. “There are lots of anti-cancer substances in the protein membrane surrounding each fat globule,” says Sally Fallon, coauthor of Eat Fat, Lose Fat. “When the milk is homogenized, those substances are destroyed.”
Many milk connoisseurs insist that the best reason for consuming non-homogenized milk is flavor, suggesting that the difference is akin to that between fresh-squeezed and reconstituted orange juice, though for some it’s an acquired taste.
This article has been updated and originally appeared as “Skimming the Truth” in the September 2009 issue of Experience Life.