It's difficult to avoid the doom-laden statistics concerning obesity rates. And at the same time, we'll no doubt be aware of the standard advice for those wanting to lose weight: "Eat less and exercise more." The problem is that evidence suggests that neither of these approaches is particularly effective for the purposes of weight loss in the long term.
Some researchers and scientists are in the process of thinking a little more creatively about the "obesity epidemic." What, some are asking, if weight is not determined simply by the relative amounts of calories taken in and those that are burned by the body?
One important factor here concerns appetite. It makes sense for individuals who want to curb any tendency to overeat, to consume foods that tend to be relatively appetite-sating. The usual advice is geared toward getting individuals to eat a fiber-rich diet because, supposedly, "fiber fills us up" and helps us "feel fuller for longer." Actually, there is good evidence that overall, protein is the part of the diet that really packs appetite-sating power.
A factor well worth considering in this controversy is the tendency for certain foods, when ingested by the body, to predispose to the accumulation of fat. While it seems obvious that the major dietary specter here is fat itself, the reality is that the prime fat-producing hormone in the body is in fact insulin. And insulin, as we know, is secreted chiefly in response to the intake of carbohydrate.
Some have theorized that weight gain can be driven by a glut of insulin. Perhaps the most famous/infamous person to put forward this theory was the late Dr. Robert Atkins. Others have come in his wake.
Recently, new life has been breathed into this concept by Gary Taubes, author of "Good Calories Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease." I've not read this book, but know enough about it and Taubes's previous work to recommend it to anyone who takes a keen interest in their (or other people's) health.
While weight gain is unlikely to be solely about insulin, my belief is that it is likely to be a major factor. Some support for this has come from a study published this month in the American Journal of Clinical Nutrition [1]. The researchers in this study basically assessed insulin levels (actually insulin levels 30 minutes after giving individuals 75 grams of glucose) in 276 people and then followed them for an average of six years each. This insulin measurement can be taken as a proxy measure of an individual's ability to handle metabolizing carbohydrate into sugar.
The authors looked at the relationship between insulin levels and certain measurements including weight gain and waist circumference. They also analyzed whether there was any difference in the results in those eating a low-fat diet compared to those in people eating a higher-fat diet.
Here, essentially, is what they found: In individuals eating a lower-fat diet, higher levels of insulin were associated with an increased risk of weight gain and an increase in waist circumference. This association was not evident in individuals eating a higher-fat diet.
Overall, in the low-fat-eating group, individuals with the highest insulin levels gained 4.5 kg (9.9 pounds) more than those with low insulin levels.
So what are we to make of all of this? The most obvious thing illustrated by the study is that higher insulin levels are associated with an increased tendency to gain weight. This clearly lends support to the idea that insulin may have a key role in weight gain.
But why would the association only be evident in those eating a lower-fat diet? I don't know for sure, but it's less likely to do with fat, and more likely to be about carbohydrates. This is because when insulin levels are high, it is generally a sign that individuals are not coping well with carbohydrate in the body and one might, therefore, imagine that eating a carb-rich diet is more likely to land people in trouble than if they were eating a lower-carb diet. Those eating a low-fat diet tend to eat a diet rich in carbohydrates, and this may explain why these individuals were the ones most prone to weight gain.
Of course, the corollary here is that individuals eating higher-fat (and therefore lower- carb) diets are likely to be less prone to insulin-induced weight gain, right? Well, though this doesn't actually prove anything, it does seem to lend support to the concept of carbohydrate-control for weight loss.
Reference:
1. Chaput JP, et al. A novel interaction between dietary composition and insulin secretion: effects on weight gain in the Quebec Family Study. American Journal of Clinical Nutrition 2008; 87: 303–309
Dr. John Briffa is a London-based doctor and author with an interest in nutrition and natural medicine.
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