Scientists are discovering there's a hidden key to shedding pounds, and it's got little to do with calories or willpower. Meet your hormones -- and the surprising effect they have on weight.
Say you eat a doughnut. The doughnut you deserve because it's a hellish day, and carbs are what will make this week -- the one before your period -- worth living through. Oh, the bliss when that powdered sugar hits your system! Until, inevitably, you crash, which leaves you exhausted and depressed... and sniffing around for another doughnut.
Because a doughnut is never just a doughnut. It's a Molotov cocktail that you're lobbing into your hormonal ecosystem.
Hormones are the chief executives of the body, governing everything: our sex lives, our stress lives, our immune response. Research has implicated hormonal imbalance in everything from breast cancer to short-term memory loss -- as well as what we eat, why we eat it, and what happens to the body once the food is down our throats. Which means that when you picked up that doughnut, you weren't just having a weak-willed moment. You were obeying your team of internal managers.
"There are at least 40 chemicals in our bodies that influence our appetite and what we eat," says Robert Greene, M.D., medical director of the Sher Institute for Reproductive Medicine in Sacramento and the author of several books on optimizing hormones, most recently "Perfect Hormone Balance for Fertility." "The good news is that we're developing strategies to shift hormone signals to help people avoid weight gain as well as lose weight."
It Starts with Good Balance
Three recent books claim that stabilizing our hormone levels is at least as important -- if not more so -- as the old equation of calories in, calories out. In "The Perfect 10 Diet," Michael Aziz, M.D., founder and director of Midtown Integrative Medicine in New York City, claims any diet will fail unless it steadies the body's level of insulin. "I know it sounds counterintuitive, but calorie counting is not everything," Aziz says. "When insulin is secreted in higher amounts, you feel hungrier and you eat more. Willpower does not exist when insulin is high."
Neuroscientist Daniel Amen's diet plan in "Change Your Brain, Change Your Body" recommends optimizing hormone levels through daily interval training, balancing insulin, sleeping well, and lowering stress.
"For your brain to be right, your hormone levels have to be healthy," Amen says. "The neurotransmitter serotonin, which affects mood and appetite, needs proper estrogen levels to be optimal. Low testosterone has been associated with a worsening of memory and mood, and more fat on your belly."
Meanwhile, naturopathic doctors Jade and Keoni Teta, in their book, "The New ME Diet," go so far as to contend that we all have individual metabolic profiles (predisposed to burn sugar, muscle, or a mix of sugar and fat), and that eating for our type will unlock our fat-burning hormones. Despite this high-concept theory, however, they prescribe -- like the other authors -- an insulin-controlling plan that emphasizes protein and fiber and restricts carbs, a basic recipe for endocrine balance.
The Hormone-Weight Link
A complex concoction of some 200 hormones circulates in the bloodstream at any given time, Greene asserts; each can signal different things to different parts of the body. The most influential for weight loss are the thyroid hormone, which helps regulate metabolism, and insulin, which allocates sugar in the bloodstream. (The doughnut prompted insulin to flood your system, directing glucose to your muscles and liver and converting excess sugar into fat. The resulting plunge in glucose led to the sugar crash.) Other hormones that may send you to the refrigerator:
This well-known fight-or-flight hormone, which drives our natural stress response, increases glucose in the blood so we have the energy to hightail it from dangerous situations... or deal with crazy-making jobs.
But according to studies, excess cortisol leads to a heightened appetite and cravings for sugar and simple carbs, as well as increased belly fat -- which is linked to cardiovascular disease, diabetes, and other health problems. (Drugstores are crammed with "cortisol blockers," but there's no clinical evidence these pills will have any mitigating effect.)
"We know cortisol results in greater food intake, particularly rewarding comfort food that's high in fat and sugar," says Elissa Epel, Ph.D., associate professor in the department of psychiatry at the University of California, San Francisco, who has studied the cortisol-appetite link. "It may be evolutionarily that during times of stress, it benefits our survival to seek food with the most calories."
A 2004 study at the New York Obesity Research Center compared overweight women who were binge eaters with those who weren't; after a stress test in which subjects submerged their hands in freezing water, the binge eaters had higher levels of cortisol.
Marci Gluck, Ph.D., one of the study's authors and a research clinical psychologist at the National Institutes of Health, agrees there's a link between cortisol, hunger, food intake, and obesity, though she admits, "What that link is, and how we might treat it, is still undefined." One thing we do know is that cortisol is regulated by sleep; several studies have shown that even partial sleep deprivation can elevate levels.
Leptin and Ghrelin
Leptin (from the Greek word leptos, or thin) signals us to stop eating if we're full. Its partner in crime, ghrelin -- the only hunger hormone identified to date -- counteracts leptin and other hormones and tells the body it's time to be fed.
Unfortunately, we can't count on these hormones to switch off when we've gotten what we biologically need from our food: Recent research suggests that these hormones of fullness and hunger play a role not just in our "homeostatic" feeding (for energy -- that is, eating to live) but in "hedonic" feeding (for pleasure -- that is, living to eat).
A 2009 study at the University of Texas Southwestern Medical Center suggests ghrelin might make some people keep eating enjoyable foods even after they're full: Mice who received ghrelin continued to push buttons with their noses to get pellets of high-fat chow long after those who hadn't received the hormone gave up.
"Human behavior, especially related to appetite and eating, is very complex," says Jeffrey Zigman, M.D., one of the researchers. He cites a 2008 study at McGill University in Montreal, in which healthy people were shown pictures of food, then some were given ghrelin. A functional MRI revealed that ghrelin activated areas in the brain involved in reward-seeking behaviors.
"What we're now showing in mice probably also happens in humans," he says. Though ghrelin goes up in periods of stress, Zigman adds, nobody knows why yet. (See a pattern here?) Notably, previous studies have demonstrated ghrelin increases throughout the day in people who have lost weight by dieting, which may help explain rebound weight gain.
Estrogen and Progesterone
After ovulation, progesterone -- the hormone that prepares the body for pregnancy -- increases, which may lead you to eat more in anticipation of needing more calories. And theory has it that when the reproductive hormone estrogen plunges in the week before your period, so may your levels of the feel-good neurotransmitters dopamine and serotonin, which your body knows will be restored by the carbs in a bowl of mashed potatoes.
Deficiencies in estrogen and progesterone may also drive menopausal women to chow down: When researcher Judy Cameron, Ph.D., removed the ovaries of 16 monkeys in a 2003 study at Oregon Health and Science University, she observed a 29 percent jump in food intake and a 3 percent jump in weight in a matter of weeks.
Hormonally challenged women may take perverse relief in the news, Cameron says: "People can say, It's not really my fault." But for our health we still have to do something about the weight gain, she notes ruefully, and recommends exercise as the antidote. (So much for relief.)
Greene's not letting us off the hook either. "Once women pass their childbearing years, it's inevitable that the reproductive hormones fall," he says. But with weight gain, fat cells expand and release hormones that promote even more fat storage. That vicious cycle makes you fatter and fatter unless you consciously interrupt the pattern."
Getting the Best Hormonal Mix
Though as yet there is no proven miracle combo of foods or behaviors that will jump-start those internal executors into setting our fat on fire, we can give our hormones a better chance by creating a stable environment in which they can work.
Eat Whole Foods
Think a diet high in fiber, complex carbs, and low-glycemic-index foods like whole grains and fiber-rich vegetables and fruit, as well as unsaturated fats, which will take longer to metabolize and help you stave off cravings, says Alice Chang, M.D., assistant professor of endocrinology and metabolism in the department of internal medicine at UT Southwestern.
Eat foods in their intact form, Greene adds: whole oranges, for instance, instead of juice. "One glass of juice might take three oranges, plus the added sugar," he says, "but if you were eating oranges themselves, you'd probably stop after one-and-a-half." Having five or six small meals of lean protein and complex carbohydrates throughout the day will help keep your blood sugar stable.
Cameron recommends exercising an hour per day, five days a week, to combat hormonal weight gain. But that doesn't have to mean a solid hour of running: "Park the car at the end of the lot," she says. "Take the stairs."
Strength-training can also help with hormonal balance, says Brian McFarlin, Ph.D., associate professor of exercise, physiology, nutrition, and immunology at the University of Houston: "It alters the cortisol level, helping you burn calories and fat. Even at rest, muscle burns more calories than other tissue."
Check Your Stress
For most people, basic stress-relief measures, such as getting a massage or seeing a counselor, "will lead to better hormonal balance," Gluck says.
A variety of research shows that people who practice yoga three times a week tend to gain less weight; one study published last year by the Journal of the American Dietetic Association found that middle-aged people who did yoga gained less weight over a 10-year period than those who didn't.
Get Plenty of Sleep
A 2004 study at the University of Wisconsin-Madison revealed that subjects who slept less had lower levels of leptin and higher levels of ghrelin. Other research has shown that just three days of sleep disruption increases insulin resistance in humans.
Raise Those Endorphins
"Part of why we eat is to get rid of bad feelings, and pleasures can counteract that," Epel says.
Ways to get that natural high? Exercise, of course. Find a hobby that engages you. Listen to music you love, and dance around your living room. Take a class. Eat spicy foods. Do something thrilling. Laugh. Have an orgasm.
Remember, not all cycles have to be vicious. Research shows the more you exercise, the better you sleep, which can make you less hungry. Also, the more you sleep and exercise, the better your mood and stress levels may be, so you're less likely to get the neurochemical cues that might lead you to overeat. And all these steps may lead you toward feeling more whole -- an even worthier goal than narrower hips.
All right, sometimes you can't resist the siren song of your hormonal cravings. These are the smartest ways to get that sugar hit.
Eat dessert right after a high-fiber meal. "The body will absorb the sugar more slowly, which allows the hormones to react more normally," Greene says.
Take it slow. In a 2010 study on the effects of eating speed, scientists gave subjects identical servings of ice cream on different occasions. At one sitting, they ate the treat in 30 minutes; at the other, they gulped it down in five. Researchers measured the subjects' insulin and gut hormones before, during, and after eating, and found that the slow eaters had higher levels of satiety due to the hormones peptide-1 and peptide YY.
Treat it with respect. "Put it on a plate and savor it," Greene says. "You'll probably eat only half as much." Our brain needs to register those rogue calories in its reward system, which takes much longer when we're guiltily stuffing them down on the sly.