Why People Don't Accept That Very Low-Fat Diets Work Best

Armen Hareyan's picture

When you really know the facts, very low-fat diets clearly make the most sense. We know that everyone wants to believe that they can eat very high-fat foods (Atkins) or high-fat foods (South Beach) and still lose weight. Why wouldn’t you want to have your cheeseburger (not cake for low-carbers) and eat it, too (without the bun, of course)? Yet, the scientific evidence clearly indicates that very low fat diets should and do work best. (If you want to read more details about this, see Chapter 2 of my book The Healthy Obsession Program (2005, BenBella Books). Now, let’s consider for reasons that help explain why all former low-carb dieters aren’t thoroughly persuaded – yet. Explanations abound for this cultural resistance to very low-fat eating. Understanding these four explanations might help you believe more clearly and fully in the dietary truth that very low fat diets work best.

Losing the Forest Because of the Trees

Which of these dietary dilemmas sounds familiar to you?
· Should I eat because I have a certain body type?
· Should I eat because of my blood type?
· Should I avoid certain combinations of foods?
· Should I discontinue eating anything with sugar?

The sheer number of recommendations about dieting could overwhelm anyone. Some of these recommendations actually conflict with each other (e.g., eat many small meals vs. don’t snack at all). Research Capsule 1-1 makes the point that most people seem very confused about basic nutrition for several complex reasons. So, how do you know who to follow to escape this dense forest of misinformation?

The pied piper, known as science, can show you the way. Scientists are those who publish in peer-reviewed journals. I’ve published more than 100 articles in such journals. These journal articles and those published by thousands of other scientists provide objective information. Such research uses well defined (and described) methods, accepted statistical tests, and other devices that allow other scientists to accept, reject, or build upon the findings. This work becomes readily available to all, in such journals as: Obesity ; International Journal of Obesity; Journal of the American Medical Association; Health Psychology; American Journal of Clinical Nutrition; Behavior Therapy; and Annals of Internal Medicine.

Very few authors of popular books, even those with doctoral degrees, have published anything about weight loss in scientific journals. Drs. Atkins (The Diet Revolution), Sears (The Zone), Agatston (The South Beach Diet), and the Hellers (Carbohydrate Addicts Diet) have doctoral degrees, but none has published in peer-reviewed scientific journals about weight loss. They have, collectively, sold tens of millions of books, but they don’t qualify as experts on weight loss. Science itself doesn’t prescribe one clear simple method for weight loss. Scientists disagree about research evidence. Knowledge gained in research doesn’t yield simple answers to complex questions. Yet, the trend in the published science of weight control clearly indicates that very low-fat diets work better than low-carb diets: better health, better weight losses, and better maintenance of weight losses.

We Americans have had our thinking about food dramatically affected by big business. Many billions of dollars have been made by those selling products that clearly increased weight problems in this country. These powerful forces continue to flood the airways and magazines with misinformation, basically communicating the desirability and acceptance of very unhealthy foods and drinks.

In his 2003 expose Fat Land, journalist Greg Critser traced the fattening of America to the aggressive and effective effort of the eighteenth secretary of agriculture, Earl Butz. In the early 1970s, Secretary Butz managed to get governmental regulation of grain sales thoroughly relaxed. This greatly improved the profitability of corn productions and the availability of high fructose corn syrup (HFCS). HFCS, six times sweeter than sugar, enabled prices to be slashed in frozen foods and improved the appearance, shelf life, and availability of high fat bakery goods (including vending machine pastries). Foods very high in fat and sugar thus became cheaper and omnipresent, contributing to the acceleration of the obesity epidemic worldwide over the past several decades.

Drs. Kelly Brownell and Katherine Horgen of Yale University wrote a remarkable treatise published in 2004, Food Fight. In a chapter entitled, “Big Food, Big Money, Big People,” they argued very convincingly that huge food and beverage companies used billions in marketing dollars to sell us obesogenic foods and drinks. These companies also entrenched themselves in schools, using substantial financial incentives to create a dependence on them by school administrators all across America.

The same marketers, who sell overpriced vacuum cleaners and unreliable luxury cars, sell obesogenic foods and gimmicky diets. Consumers remain susceptible to believing slick, logical, repeated, catchy pitches. Books with authors who seem credible and charismatic and whose books have appealing titles and premises can sell millions – if marketed aggressively and cleverly. If it gets on TV, it seems, at least, acceptable.

Scientists do their work quietly. We receive no payment for articles published in scientific journals, even in the best journals in the world. Scientists rarely publish books like this one. These “trade books” take considerable time and specialized writing skills. They also demand a willingness (eagerness actually) to do scores of interviews, travel, and other things that take even more time and effort, often with modest payoffs.


You can see why capitalism creates and sells more books than science. Millions get poured into creating and selling trade books, even lousy ones. Billions get spent convincing us that foods that contribute to weight gain are just fine, normal, part of the greatness of our culture. How can objective sciences, gathering dust in obscure journals, compete with that for your attention?

Spurious Correlations

In the late 1800s, some medical authorities believed that riding in trains caused Syphilis. This venereal disease had spread widely and caused madness, then a torturous death. Some physicians believed that bouncing on trains must cause this “nervous disease.” After all, they asserted, traveling salesmen often get Syphilis and priests rarely contract it. The salesmen bounced on lots of trains, whereas priests did not.

Decades later a bacteria was discovered that caused the disease via direct contact, usually during sexual intercourse. Although traveling salesmen did ride trains more than most, they apparently had unprotected sex more than most, as well. Train riding was coincidentally associated with Syphilis (a classic spurious or false correlation), but trains didn’t cause it.

The authors of the recent spate of low-carb diets have argued that Americans gained lots of weight in the past 25 years – just as they became increasingly aware of the desirability of eating less fat. Therefore, they have claimed, low-fat diets cause weight gain by encouraging people to eat too many carbs.

Awareness of the importance of low-fat eating spuriously correlated with Americans gaining weight. Just because we Americans increase our awareness of the value of eating less fat didn’t result in Americans actually eating less fat. Americans ate about 80 fat grams in 1980 and in 2004. That awareness also didn’t cause Americans to gain weight. Eating more calories, continuing to eat too much fat, and failing to stay active, among other things, caused the weight gain.

Using the before-and after- testimonials to sell something also relies on spurious correlations. Just because your neighbor Mary lost weight when she used a low-carb diet, doesn’t mean that the diet caused weight loss. Perhaps Mary significantly increased her workouts just when she started the low carb diet. Perhaps she started taking medication that decreased her appetite just when she started. Perhaps she consciously decided to eat less (total calories) just when she started. If Mary took any of these steps, then her weight loss was associated (correlated) with beginning a low-carb diet, but not caused by it.

The Dosage Problem: Very Low-Fat Diets Work Better than Low or Moderate Fat Diets

“I had a splitting headache. I took ½ of an aspirin and it did nothing! Aspirin just doesn’t work for headaches.”

Two aspirins, not half of one, can reduce typical headache pain. In a similar vein, very low-fat eating, but not moderate-fat eating, leads to substantial and well maintained success in weight control. Most Americans currently consume about one-third of their calories from fat. America will continue to gain weight rapidly, as it has in the last few decades, unless it can change that percentage to about 10% of calories from fat. Many health oriented groups do not recommend such a stringent standard, partly because they don’t think people can do it. But, this only contributes to America’s failure to lose weight and keep it off. If you decrease your percent of calories from fat from 34% to 30% (as recommended by the American Heart Association, for example) you won’t lose the weight or keep it off. You may as well take a half-aspirin when you have a splitting headache and expect that to work, as well.


Successful weight loss and maintenance of weight loss requires consistency. Weight control is not a part time job. These four explanations help make sense of people’s resistance to accepting the value of very low fat eating. Now is the time to make the switch to very low fat eating if you’re serious about losing weight permanently.

Written by Daniel Kirschenbaum, Ph.D., ABPP