Harvard nutrition professor Dr. David Ludwig recently gave an interview to the New York Times, in which he discussed the central ideas of his forthcoming book, Always Hungry, which offers a solution to the obesity epidemic afflicting much of the Western world today.
A lot of what he says makes sense, but it seems to contradict what most experts in nutrition, health, and obesity currently believe to be true. Here, we take a closer look at what we know about weight gain and fat loss, as well as Ludwig's claims based on his New York Times article.
The Glycemic Index and Weight Loss
The argument that high glycemic index (GI) foods are primarily to blame for the obesity epidemic today has several holes. For starters, comparing the effects of eating foods with a low glycemic index to those with a high glycemic index on weight loss has consistently shown similar results in randomized controlled trials.
Some research suggests that eating high-GI foods may hinder your efforts to lose weight and even contribute to gaining weight, but other studies have found no such link. The glycemic index has not been shown to have any significant impact on weight gain or loss in the majority of studies.
Even if we grant the possibility that high GI foods contribute significantly to the issue, this still leaves the vast majority of our worst offenders unaccounted for. Low-GI versions of cookies, ice cream, pizza, burgers, shakes, potato chips, and candy bars are widely available. How is this possible with all the sugar and processed carbohydrates they contain?
Metabolism and Calories-In, Calories-Out
Reducing calorie intake can cause a person to feel more hungry and slow their metabolism. When combined with increases in activity and exercise, however, a slow and steady reduction in caloric intake (1% per week) has little effect on increasing hunger and slowing the metabolism.
Indeed, the following case can shed light on weight loss and the fact that changing one's diet is not the only way to achieve this goal.
Let's say a 250-pound person loses 10% of their body weight and stops their fat-burning program entirely. After a few months on the plan, the person would have lost enough weight to weigh 225 pounds.
Blood Sugar and Weight Gain
Even though being overweight is commonly associated with an abundance of food, it more closely resembles hunger than we might think. Too much calorie storage in fat tissue prevents the brain from receiving the fuel it needs to maintain an efficient metabolic rate. Even when fasting, the blood sugar and lipid levels of overweight and obese people are higher, not lower. Claiming that people with higher levels of body fat have an undernourished brain is not just inaccurate or misleading; it's the complete opposite of the truth.
Fat Loss and Weight Gain
If you eat healthily, your body will shed excess fat, just like a fever would subside if You addressed its underlying cause. The claim is contained in this statement. Weight loss will be simple and quick if you follow the plan, and your whole life will improve if you do. While this is true for the type of diet Ludwig advocates, it is also true for virtually every other diet that has ever been tested. Losing weight is guaranteed if the diet causes a net decrease in daily calorie consumption.
The main issue is that this weight loss, again across almost all diet types, isn't sustainable in the real world by real people over months and years after the weight loss has occurred. Ludwig proposed the low glycemic index (GI) whole foods diet is only as effective at maintaining weight loss over the long term as any of the other countless diets studied.