Preventive medicine: carbohydrates, calories and clickbait

A fascinating and well-conducted randomized trial of 164 adults, recently published in the BMJ, indicating that following a low carbohydrate diet to maintain weight loss can increase energy expenditure, as one could expect , attracted the attention of the media. Some of the most prominent entries in this wave of brief attention, including the coverage of The Chicago Tribune and the New York Times, give a false representation of the results of the study.

These two articles on the study play the role of a popular fantasy that weight loss can be dissociated from calories. But this assertion, formulated in the media coverage of the study, but not in the well-written study document, is totally at odds with the way the study was conducted.

The authors initially enrolled overweight adults and all of them submitted to the same dieting. How did they get people to lose weight? By limiting calories, as they clearly and explicitly state in their own words: "During the break-in phase, energy intake was limited to promote weight loss by 12% (less than 2% ) over a period of 9 to 10 weeks.

The researchers again turned to calories when it was necessary to adjust the weight during the intervention. Here are words copied directly from the research paper: "We randomly assigned participants who achieved the weight loss goal in high, moderate, or low carbohydrate test diets during a 20-week test phase. During the test phase, participants' energy intake was periodically adjusted to maintain weight loss within 2 kg of the pre-randomized level. "

Perhaps, given the ridiculous noise that has been made about calories, does this last thing need to be repeated once again: "… the participants' energy intake was adjusted periodically…". In other words, even in this study, we explicitly examine the metabolic effects of carbohydrates. At the time of inducing weight loss or ensuring that it was maintained, the researchers turned to calories both times.

The main conclusion of this study is that energy expenditure – by still unknown means – increases as carbohydrate intake decreases. This is not a rebuttal of the importance and relevance of calories and energy balance, but a reaffirmation of it. Calories matter, and if you want to lose weight and keep it off, you need to burn more first, then as much as you eat each day. If a low carbohydrate diet helps increase the calories consumed, it would help to lose weight and maintain weight, but at higher levels of calories. An increase in energy expenditure is therefore not the "price". The price would be an easier way to lose weight without taking it back.

A large amount of information on weight, in populations and individuals, in clinical trials and elsewhere in the world, however, does not show this effect. Millions and millions of Americans have followed every type of diet imaginable in recent decades, including many versions of a low-carb diet since at least the 1970s; but maintaining weight loss is the exception and not the rule.

Despite the sequential popularity of many low carb branded diets (such as Atkins, South Beach, etc.), the prevalence of obesity in the general population continues to worsen. In RCTs comparing dietary types, those assigned to a low carbohydrate diet regained weight just as easily as all other diets.

I think this new document in the BMJ is of very high quality and very intriguing. Could macronutrient transfers, in the context of healthy diets, change energy expenditure? Could he have more than one? Do these effects generalize or affect only a few of them? Are these effects maintained or mitigated over time by compensatory mechanisms? Important and worthy questions, all.

But these were calories that these researchers relied on when they needed their study participants to lose weight. Calories count, even if counting them is not the best way to control the number of calories consumed. for that, focus on the consumption of high quality foods. Macronutrient thresholds tell us little about the quality of food, and it is the quality of food that matters most for the evolution of health over the course of life .

Pepperoni is not good for you. The donuts are not good either. But maybe the clickbait comment and the diet-study-title-whiplash are even worse for you.