Sandra Aamodt is a neuroscientist. She has a very, very pessimistic view of weight loss. Far more pessimistic than Linda Bacon in Health at Every Size. Bacon wrote:
…the best way to win the war against fat is to give up the fight. Turn over control to your body and you will settle at a healthy weight. And regardless of whether you do lose weight, your health and well-being will markedly improve. You will find that biology is much more powerful than willpower.
Aamodt’s advice is to learn to eat mindfully — eating when you’re hungry, stopping when you’re full — in an effort to mitigate eating disorders and stop gaining weight. Your best bet, she says, is avoiding diets because they will, in almost every case, cause you to get fatter. She explains how the body’s systems for controlling weight are like a home thermostat. You can open a window in the winter and cool things down, but the thermostat is still set where it’s set and it works to regulate the temperature of the home. Similarly, you can do drastic things to lower your weight, but your internal thermostat is still set where it’s set and your body will still work to regulate your weight back to it’s set point. Often it overshoots and you wind up fatter.
In Aamodt’s talk, she uses one chart. It looks at four healthy behaviors: improving nutrition, increasing exercise, not smoking, and drinking in moderation. While people with normal weights show an increase in health with each of these behaviors that they adopt, it’s obese people who show the biggest increase when just one behavior is adopted. When people who are of normal weight and people who are obese adopt all four, the difference in their levels of health nearly disappears.
If you look at the chart, you can easily see that it implies that having a BMI of more than 30 is a significant health risk for someone who doesn’t eat well, doesn’t exercise, who smokes, and who drinks a lot of alcohol. Adding in just one healthy behavior doesn’t make much difference for those with BMIs below 30, but does for those with higher BMIs. By the time you get to all four behaviors, it’s a pretty even playing field.