Calories Count

A study of more than 800 overweight adults by The New England Journal of Medicine demonstrates a simple fact: Weight management is mainly about calories in, and calories out, however we distribute the carbs or fat in our diet.

This week, I’ll dispense with all suspense and give you the punch line up front: Einstein was right. Matter and energy really do relate in a predictable manner. Or, in other words, calories do count.

This, in essence, is the takeaway message from a clinical trial of more than 800 overweight adults just published in the prestigious New England Journal of Medicine demonstrating that the same amount of weight was lost over two years no matter how macronutrients were distributed.

For far too long, we Americans have been feasting on a diet of decidedly silly food for thought. We interpreted advice to cut dietary fat as a license to ignore every other principle of healthful eating, and eat Snackwell cookies until they came out our ears. Predictably, we did not slim down.

We then got advice to cut carbs, which was silly enough to begin with, even before it morphed into a license to consume the likes of low-carb brownies featuring copious additions of trans fat.

To anyone still inclined to think our previous methods made sense, or that we can overlook overall nutrition and get to better health and/or slimness one nutrient class at a time, I pose this simple question: Where the heck are all the skinny people?

Fundamentally, the new study -- a large and methodologically strong clinical trial -- shows that weight loss is achieved by creating a calorie deficit; period. Whatever the proportion of macronutrients carbohydrate, fat, and protein- in the diet, if a net deficit in daily energy balance is achieved, weight will be lost.

In general, this will confer benefit across a wide array of biomarkers for chronic disease risk as well. The benefits seen in the current study -- affecting blood pressure, lipids, insulin and glucose, to name a few -- are partly due to improvements in dietary intake, partly due to weight loss per se. The study did not include any means to make these attributions differentially, so we are left with the aggregate benefits of both influences. Eating well improves health; so does weight loss if you are overweight.

The study does not in any way exonerate the various popular diets that have espoused restrictions of one macronutrient class or another, even though it shows that weight can be lost and health improved no matter which macronutrient class is restricted, and which is emphasized.

The authors were emphatic and clear that they created comparably healthful diets differing in macronutrient distribution. So, for example, all diets provided at least 20 grams of fiber daily, even the low carbohydrate assignments. This is not at all characteristic of popular low-carb diets. All of the assignments restricted intake of saturated fat, also not characteristic of popular low-carb diets.

In fact, if anything, the study was unduly “kind” to low-carb diets, and a bit unfair to low-fat diets. The real-world low-fat, high-carbohydrate diets that are most sensible are mostly plant-based, and thus offer a very high intake of fiber and a very low intake of saturated fat. The real-world low-carb diets tend to result in very low fiber intake, and relatively high intake of saturated fat.

By: Dr. David L. Katz*

Missing from the comparison groups in this study is a truly “optimized” diet. That is an observation, not a criticism; the study did what it set out to do. Still, I would like to have seen how an optimally balanced, reduced-calorie diet did in the mix.

An important limitation to the study is that the assigned treatments were approximated, but not actually achieved. Participants didn’t quite manage to follow the diets to which they were assigned, although all moved in the right direction.

This highlights the fact that changing dietary intake pattern is hard to do -- even with a great deal of hand-holding. My recent efforts have been focused on this very issue, and seek to empower dietary change one well-informed choice at a time, rather than in one fell dietary swoop.

One final, important element of interpretation here: the authors conclude that diets across a wide array of macronutrient distribution may be recommended, with comparable benefit likely to ensue. That is only true if the same care is taken to the healthfulness of those diets as was the case in this study. In the end, the influences of diet on health are not just about the relative quantity of macronutrients, but about their quality as well.

This crucial consideration is all too often overlooked: Both salmon and salami are high in fat; lentils and lollipops are both high in carbohydrate. In each case, one differs from the other as night from day in overall nutritional quality.

There may be subtle differences in the ways macronutrient classes up -- or down -- regulate their own oxidation, and in the efficiency with which each is burned. And there are other, subtle nutrient influences on energy balance as well; capsaicin, for instance, the primary substance that makes spicy food hot may augment postprandial thermogenesis, the loss of calories as heat following a meal. This represents a slight increase in calorie burn.

But all such effects sum up to the proverbial drop in the bucket -- and both the bucket, and the flood tide carrying us toward ever higher rates of obesity, are full of calories. At the end of the day, weight is about calories in, and calories out -- and all the rest is a drop. The noise that drop makes as it falls into the bucket may be full of sound and fury, but we should all know what it signifies.

Einstein was right: Energy and matter interrelate, predictably and inescapably. It is the amount of energy (calories) in the food we eat that determines the amount of matter (mass) we store in our bodies. There are better ways to achieve a healthful, satisfying, pleasurable and balanced relationship with food than by counting calories.

But there is no denying that when it comes to weight, calories do count. No need to take my word for it; I’m just citing the New England Journal, and paraphrasing Einstein.

* Dr. David L. Katz is an Adjunct Associate Professor of Public Health
and Director of the Prevention Research Center at the Yale University School of Medicine.
He is and Editorial Advisor to Prevention Magazine, Columnist for O, the Oprah Magazine,
and a Medical Consultant to ABC News. He may be reached at www.davidkatzmd.com.