Carbs Still Don't Make You Fat. But Taubes' Words May Make You Crazy

Don’t do it! Don’t dump your carb-rich foods because of yet another Gary Taubes’ article, which hand picks research to make for sensational headlines that successfully get propagated in the NY Times (albeit just in the Opinion section, not the Science one, thank God!) Yes, yet another news piece inappropriately attacks carbohydrate, failing to note the study’s limitations and the risks of jumping to irrational conclusions.  I’m no researcher but I’m a critical reader of research. And I find Taubes’ (and other such articles drawing false conclusions) simply appalling.
Serve with a Greek yogurt and include the nuts and the
glycemic load is lowered. Better than given this favorite up!

Taubes pulls from a recent study by Ludwig and colleagues at two well-respected Boston hospitals. The objective was to examine the effects of 3 diets with different composition of protein, fat, and carbohydrate and glycemic load, on metabolism. This was done on overweight and obese 18-40 year olds following a weight loss of 10-15%. Glycemic load refers to how much a food will raise blood sugar compared with a standard. It takes into account the amount of carbohydrate in a food, as well as the impact of that food on blood sugar.

Here are a few facts to consider. Taubes' carb-bashing article ignores some critical points, many highlighted by the study authors themselves:

• Total sample size of this ground-breaking study? 21—an embarrassingly small size to be drawing such global conclusions! Perhaps even more striking is that the study began with 32 participants--that's a 34% drop out, in spite of a $2500 financial reward for full participation. I am left wondering why such a high drop out rate? These were self-selected participants, in response to an ad. Were the results not as satisfactory in those that dropped out? We'll never know, but I could only guess that if they were satisfied with the weight loss and maintenance results they might have been inclined to stick with the study. If we had all 32 starting participants perhaps the results would be quite different.

Carb-rich wheatberry salad--a summer favorite!
One of 25 recipes at
• The study looked at the impact of three different diets after weight loss, which might be quite different than the impact on those whose weight has been stable. The body does act differently after being starved!

• 1 month per diet type only! That’s how long the study evaluated these various diets.

• Even if this were all valid, would the subjects actually gain weight? It is unclear, given these were not free-living conditions and resulting weight changes were apparently not explored. In fact, we have no evidence of how closely these diets were actually followed, given this was an outpatient setting. The study mentions likely predictors of future weight change (such as changes in metabolic rate), but no actual weight change data on each of the diets is described. Yet Taubes certain jumps to this conclusion.

• Even if they did gain more on a higher carbohydrate diet, there were 2 very negative effects of the lowest carb diet, that may result in long term serious consequences.  Both urinary cortisol levels (a hormonal measure of stress) and C-reactive protein (a marker for chronic inflammation) increased. And both of these are associated with increase risk of cardiovascular disease.

• With the most minimal effort on Pub Med, I found another study on the pediatric population exploring high and low glycemic load meals on energy intake, satiety and hunger. Guess what this study concluded? That there is no evidence for this population (of Hispanic youth) that changing the glycemic load effects short term hunger, fullness, satiety or energy intake. BTW, this one was also by Ludwig and colleagues. In fact, even in the study Taubes reports on, there is no advantage in terms of subjects sense of hunger on the three different diets.

• The authors of the study (not Taubes) state: 
Low carb? absolutely! But not without its risks.
"These findings suggest that a strategy to reduce glycemic load rather than dietary fat may be advantageous for weight-loss maintenance and cardiovascular disease prevention."  
Yes, reducing your intake of fat to very low levels is quite senseless. But no one is advocating for a diet rich in saturated fats, like those found in the meat above. Yes, fats are a welcome addition to diets, even for those watching their weight! And key words to note here are "glycemic load". In other words, think balance. Meals with a combination of protein, fat and carbohydrate will have only a moderate glycemic load, and that is what may be key--both for metabolic health, psychological well-being (think avoiding deprivation) and long term adherence. Yes, the study authors have the wisdom to add:
"Ultimately, successful weight-loss maintenance will require behavioral and environmental interventions to facilitate long-term dietary adherence." And they acknowledge that the study diets were not designed for long-term practicality, and that the very low carb plan would be difficult to follow long term.

Having worked with many thousands of individuals to manage their weight, I stand 100% behind including carbohydrate to do so. Carbohydrate-rich foods are a necessary, satisfying, and energizing part of a healthy diet. I urge caution to the public, which may be less experienced at reading such strong-stated opinions as Taubes' as if they were fact.
Next Post »