Aspen Ideas Festival: The human brain’s attack on weight loss
June 26, 2016
There are more than 175,000 diet books currently listed on Amazon. Millions will be sold, and some people might even lose the weight they set out to lose, but almost all of them will gain it back.
That was one of several grim dieting truths revealed during seminars in the Spotlight Health program track "The Future of Food: The Hype, Our Health" at the Aspen Ideas Festival on Friday and Saturday.
Neuroscientist Sandra Aamodt, author of "Why Diets Make Us Fat: The Unintended Consequences of Our Obsession With Weight Loss," talked about what scientists call the body's defended range, a 10- or 15-pound weight range in which our brains want our bodies to remain.
"The reason they call it the defended range is because your brain will fight like crazy to keep you in it. And particularly keep you from going below it," she said. "And when you do drop below the weight that your brain thinks is correct for you, what happens is that it tries every trick in the book to get you to gain that weight back."
Those tricks include increased hunger, making food feel more rewarding and a changed metabolism.
"The brain areas involved in addiction and food rewards are more strongly activated in people who are below their normal weight than those in their defended range," she said.
Recommended Stories For You
Because the human brain hasn't evolved past the days when food was scarce and humans had to work hard to hunt and gather it, systems within the brain operate in a different time, almost in a completely different world.
"We're living with a brain that evolved to solve a completely different problem than the problem that we have now," she said. "We have a brain that evolved to be extremely talented in keeping us from starving to death."
Weight and children
During the Friday session, "What Is Healthy Eating and Why Does the Brain Resist It?" Aamodt and other panelists talked about why it's important for children to learn healthy habits from an early age. When the brain works so hard against our quest to be thinner, it's critical for humans not to add fuel to the fire.
Food preferences are largely formed in childhood, so parents have to keep healthy foods around instead of junk in order to help shape healthy habits, Aamodt said. She cited research at her Saturday morning session "Why Diets Don't Work" that proves one of the predictors of weight gain over time is one's dissatisfaction with their body as well as other people's dissatisfaction with their bodies.
"Do not ever tell your kids that they're fat. Do not ever tell your kids that they're getting a little chubby, or, 'Maybe you might want to start watching what you eat, little darling,' or any of the things that your kids hear perfectly well as, 'My mom and dad don't think my body is good enough,'" she said. "Bad mistake. Don't do it. It creates eating disorders, and it creates weight gain."
The research-tested way to raise children who develop healthy habits, thus less likely to struggle with weight, includes healthy eating at home, home-cooked meals, fun exercise and not talking about body size at home.
Even a parent who talks about their own weight in front of their children can have enormously negative effects, she said.
"No 'I'm fat,' no 'You're fat,' 'That guy on the TV is fat,'" she said. "Just focus on healthy behavior, and make that a regular part of your life."
Public interest breeds confusion
Dariush Mozaffarian, a cardiologist and the dean of the Friedman School of Nutrition Policy at Tufts University, said nutrition is the biggest issue affecting patients, yet he learned almost nothing about it as a medical student. There has been an explosion of public interest on the subject, but that also means more talking heads that can confuse the areas of scientific consensus.
"There's enormous confusion on what to eat," Mozaffarian said, adding that a fear of fat has been replaced by a fear of calories.
The focus should be on increasing consumption of the foods that are good for us — nuts, seeds, beans, fruits, whole grains, fish with omega-3 fatty acids and yogurt for its probiotics.
Foods to avoid include refined grains, starches and sugars, and processed meats like bacon and lunch meats. More neutral foods that aren't necessarily good or bad include cheese, eggs, butter and chicken, he said.
Both Mozaffarian and Aamodt, as well as Saturday afternoon speaker Kevin Hall, a physicist with the National Institutes of Health, stressed that weight and health don't go hand in hand. America is obsessed with weight, but there's a lot of research that shows overweight people can still be healthy and normal-weight people also can be unhealthy.
"Healthy habits, healthy behaviors are far more important to health than weight," Aamodt said. "Your doctor encourages you to lose weight, which your brain will fight forever, but it's not fighting you to get more exercise or eat more vegetables."
Hall has conducted research on calories and metabolic rates that he talked about in a Saturday session called "Myths of Dieting and Weight Loss."
One of the ways the brain fights weight loss is by slowing down the resting metabolism in folks who have lost weight, as evidenced by a study Hall helped conduct that followed "Biggest Loser" contestants for six years after the show.
"Metabolic adaptation is kind of like a spring. If you're not doing anything in your lifestyle to try to change your weight, the spring is relaxed," he said. "If you want to lose weight, you're going to have to stretch the spring, and it's going to pull back on you in proportion to how hard you're pulling on it. The harder you pull on it, the more weight you lose."
So what's the secret to maintaining successful weight loss? Hall said people who maintain weight loss have three things in common — they eat breakfast, they weigh themselves regularly, and they exercise a lot. Aamodt said she found success with maintaining her desired weight by never weighing herself, exercising every day and practicing mindful eating — in other words, eating when hungry and stopping when full.
While there are no real secrets to successful long-term weight loss — especially with a brain that constantly works against us — the speakers agreed that healthy lifestyle habits do offer hope for success.