How Diets Lead to Weight Gain

How Diets Lead to Weight Gain

How Diets Lead to Weight Gain

How Diets Lead to Weight Gain

Your Brain Thinks Diets Are Starvation

Many dieters find themselves behaving like starvation victims. Trying to only eat 1,500 calories a day and an hour of exercise a day—is what most of us would call a sensible weight-loss diet. That’s what we did for most of my adult life whenever we think we are too heavy.

We may believe that losing weight is a good idea, but our brains often don’t agree. Someone who starts at four hundred pounds and then loses one hundred pounds has lost 25 percent of his body weight, and his brain changes his physiology in much the same way. Most dieters who’ve lost a lot of weight respond to food restriction as if they were starving to death, by developing an intense drive to eat.

Scientists have known about this psychological response for almost half a century, since Jules Hirsch reported the results of his early weight-loss studies in 1968. Rockefeller University had an inpatient facility that allowed scientists to observe what happened when obese people lost weight. The participants were highly motivated, as they were willing to spend sixteen to twenty weeks living away from home on a liquid diet that provided only six hundred calories per day. Hirsch and his colleagues had long been puzzled by the fact that the people who lost weight in their program always seemed to regain it when they went home, despite claiming that they wanted desperately to remain thin. To figure out what was going on, he put together a multidisciplinary team that could evaluate everything from the participants’ physiology to their mental state.

The psychiatrists found no behavioral or psychological problems in the obese participants when the study began. To no one’s surprise, the dieters were grumpy and hungry during weight loss. Other psychological symptoms, though, persisted after weight loss ended. The formerly obese people were mentally and physically sluggish. They showed increased anxiety and depression, along with an intense obsession with food, including dreams and waking fantasies about food and eating. Perhaps as a consequence, they also admitted to breaking their new diets repeatedly, often eating in near-uncontrollable binges. The researchers were struck by how much these responses resembled the psychological and physiological consequences of starvation.

Dieters Get Fatter in the Long Run

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Like starvation, dieting is a strong predictor of future weight gain. Fifteen long-term studies, which followed dieters for one to fifteen years, all found that dieters are more likely than no dieters to become obese. That’s true in men and women, across various ethnic groups, from childhood through middle age. The effects are strongest in people who started dieting when they were in the normal weight range, perhaps because weight loss reduces their muscle mass the most. When dieters regain their lost weight, they gain fat faster than they gain muscle, which leads them to replace muscle with fat or to recover their strength at the cost of putting on extra weight. People and laboratory animals with a genetic tendency to gain back more weight than they lost may produce additional fat cells during the regain process, providing a place to store more weight. These results suggest that dieting may be counterproductive for many people, as it leads to weight gain, on average, rather than loss. At best, for people (like me) who don’t regain more weight than they’ve lost, it’s merely useless.

Because people in such studies aren’t randomly assigned to diet, some experts argue that the relationship goes in the other direction: people who are genetically prone to weight gain are more likely to try to lose weight. That line of reasoning presumes that normal-weight people who start dieting were already gaining weight beforehand, due to their susceptibility to an environment of food abundance. No doubt that’s true in some cases, but it strikes me as unlikely to be the whole explanation. Most of the teenage girls I knew didn’t start dieting because they were gaining weight. Instead we wanted smaller bodies than we naturally possessed.

To sort out the influence of genetic predispositions from dieting itself, researchers did a nine-year study of more than four thousand twins, from the ages of sixteen to twenty-five. Among identical twins who started at normal weight, when only one twin was a dieter, that twin was more likely to gain weight than the no dieting twin over the next nine years, indicating that dieting can increase weight gain after accounting for genetic background. The difference in weight gain between dieters and no dieters was even larger among fraternal pairs, though, supporting the idea that dieters may also have a higher genetic tendency toward weight gain. A single episode of deliberate weight loss in this study increased the odds of becoming overweight by a factor of two in men and a factor of three in women. Women with two or more episodes of dieting were five times as likely to become overweight by age twenty-five.

Another way to test this idea is to look at people who had an external motivation to lose weight, like the starvation-experiment participants. In his early twenties, Michael Vassar went on a diet, although he wasn’t worried about his weight. Instead, as a futurist working at the Singularity Institute for Artificial Intelligence in San Francisco, he was intrigued by research showing that long-term calorie restriction can extend lifespan in insects and rodents. Along with other enthusiasts, he hoped to show that this approach would work in people as well. To do so, he aimed to eat 1,400 calories per day, reducing his weight from 150 pounds to somewhere in the 120s.

He developed a series of rituals to control his eating. To make sure that he didn’t eat thoughtlessly, he required himself to state his intent to eat out loud before he took the first bite of anything. If he was still hungry, he had to wait half an hour before eating again. With experience, he became an expert on hunger, aware of the trade-offs of one food choice over another. He learned to avoid muffins and pastries, which were too difficult to eat in moderation. When he ate less, he discovered that food tasted better. Living in the Bay Area made the experiment easier, as “life-hacking” projects like trying to manage on less sleep were routine in his social circles.

The diet definitely had drawbacks, though. Because his metabolism was suppressed, he felt cold almost all the time, except when he was directly in the sun on a warm day. His body temperature was ninety-five to ninety-six degrees, and his sex drive disappeared. Eighteen months after beginning the diet, he moved to Kazakhstan, where winter temperatures average four degrees below zero Fahrenheit, to work with the Peace Corps. He decided that such a cold climate was incompatible with calorie restriction, so he stopped dieting and allowed himself to eat normally. He regained all the weight that he’d lost and more. Discussing his experiences fifteen years later, he says his current defended range centers around 165 pounds, though he weighs 175 pounds at the moment. Losing about 20 percent of his body weight appears to have led Vassar’s brain to defend a higher weight range, even though he had no history of concern about his weight.

A history of repeated dieting starting from a normal weight is also typical of people who participate in weight-conscious sports like boxing or wrestling. Such dieting presumably has no connection to a genetic predisposition toward obesity. Elite athletes who competed for Finland in those sports gained more weight by age sixty than their peers who had competed in sports that didn’t require weight regulation. The dieters were three times more likely to be obese.

How Diets Promote Weight Gain

Why would dieting make some people gain weight? The explanations relate to a central truth about diets: when people lose a lot of weight, from any starting weight, their brains declare a starvation state of emergency. The solution to that emergency is to gain back the weight—and perhaps a little extra reserve to get them through the next famine.

One reason that dieting might lead to weight gain is that dieting is stressful. From the brain’s perspective, dieting is starvation. As we’d expect in that case, calorie restriction produces stress hormones, in people and also in mice. Across a wide variety of species, stress leads to weight gain, and particularly to increases in abdominal fat, which is the type of fatness most strongly associated with medical problems. Yet stress is also a consequence of weight gain, forming a vicious cycle in which people gain weight, making them (and others) unhappy with their bodies, and the resulting stress causes them to gain yet more weight.

Popular opinion has it that people gain weight because they lack self-control, but little evidence supports this idea. The research suggests instead that attempts to exercise strict control over food intake tend to backfire, often leading to weight gain by strengthening the drive to eat. (No one ever said that biology was fair to dieters or anyone else.) If we think of increased hunger as a response to involuntary starvation due to a famine, that motivation to eat makes more sense.

In a large body of work over half a century, psychologists Janet Polivy and Peter Herman studied two types of eaters. Controlled eaters routinely watch their weight. They count calories, keep food diaries, and think carefully about the consequences before choosing what to eat. They often feel guilty when they eat something that wasn’t in their plan. Sounds great, right? That’s exactly what most weight-control advice tells us we should do, whether it comes from annoying relatives or newspaper columnists or the family doctor.

Unfortunately this advice doesn’t work for a lot of people. The constant preoccupation with food uses up willpower and reduces performance on other tasks requiring executive control, like doing a good job at work or parenting. Controlled eating also reduces the influence of the brain’s energy-balance system by teaching people to rely on external cues to regulate their eating. In our modern environment, the vast majority of those cues say “Eat! Eat! Eat!” After all, marketers designed a lot of them to get customers to buy more food. When we exhaust our willpower and ignore our hunger, the reward and habit systems take control of eating choices.

In contrast, intuitive eaters are sensitive to their bodies’ signals, so they eat when they’re hungry and stop when they’re full. The research papers refer to controlled and intuitive eaters as “restrained” and “unrestrained” eaters, respectively. I don’t use those terms because an unrestrained eater sounds like someone out of control who spends his days gulping down Doritos and cartons of ice cream. That’s a completely misleading impression. Instead, because of their internal focus, intuitive eaters are less vulnerable than controlled eaters to advertising, super-sizing, stress-induced eating, and the all-you-can-eat buffet. They are less likely to become overweight, maintain more stable weights over time, and spend less time thinking about food. Long-term dieters, in contrast, are more likely to eat for emotional reasons or simply because food is available, which makes eating less responsive to the body’s calorie needs.

Your Inner Rat

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Another reason diets lead to weight gain is that starvation makes people more susceptible to binge eating. From an evolutionary perspective, this makes sense. If food was hard to find yesterday and may be hard to find tomorrow, then we should eat as much as possible today. Although we often attribute human binge eating to complex psychological motivations, rats share the same basic biology.

In a typical human experiment, some volunteers drink a milkshake, while others get nothing. Then both groups taste and evaluate snacks like ice cream, nuts, and cookies. The researchers don’t let on that they’re interested in how much of the tasty food participants eat, not how much they enjoy the snacks. Intuitive eaters tend to eat fewer snacks after the milkshake, as we’d expect that the brain’s energy-balance system would lead them to do. Controlled eaters, on the other hand, eat less when they aren’t given the milkshake—and stuff themselves full of snacks after the milkshake, whether the serving is small or large.

This surprising behavior happens because controlled eaters figure they’ve already blown their diets by drinking the milkshake, so they might as well eat the foods they’ve been denying themselves. Follow-up studies provide evidence for this interpretation. If the experiment instead begins with a salad, which has the same number of calories as the milkshake but doesn’t make controlled eaters feel like diet cheats, then they maintain control in the snacking phase. Drinking alcohol, doing an earlier task requiring willpower, or being emotionally upset also makes controlled eaters lose control.

The resulting alternation between food restriction and overeating may explain why controlled eaters generally weigh more than intuitive eaters. To be sure, though, we must consider the possibility of reverse causality. People may become controlled eaters because they recognize their own tendency to overeat, which could explain why they continue to gain weight because (say it with me now) diets don’t work. As genetics influence weight and eating behavior, the most reliable evidence that food restriction causes overeating comes from a study of almost 1,600 identical and fraternal twins. The results are consistent with research that doesn’t take genetics into account. Controlled eaters weighed more at the beginning of the study, showed more weight variability, and had gained more weight four years later than intuitive eaters. This association between controlled eating and weight remained significant in twin pairs who shared both genes and childhood environments, with the weight gain difference between a controlled-eating and an intuitive-eating identical twin being three to six times higher than the average difference between twins. Another twin study found no genetic influence on weight variability or yo-yo dieting, suggesting that these traits result from life experience.

In both adolescence and adulthood, controlled eaters are more likely than intuitive eaters to develop binge eating in studies that follow participants over time. This effect is strongest in people with a high genetic risk of binge-eating disorders, as shown in a study of almost 1,700 twins. Teenagers who use the weight-control strategy of fasting on certain days have a higher risk of developing a binge-eating disorder within the next five years than their peers who are controlled eaters but do not fast. Taken together, all this evidence suggests that repeated dieting probably won’t lead to permanent weight loss but does increase the odds of future weight gain due to overeating.

The “diet-breaking sinner” effect is familiar from my own history. If I went over my calorie budget for the day, I would usually spend the rest of the day eating whatever I wanted. “One Snickers bar, and I might as well just weigh three hundred pounds. My mind tends to that black-and-white thinking: either I’m good or I’m not. If I break down and go over my calories, then I can go eat another thousand calories from the pantry.” binges felt out of his control. “I would find myself eating and eating and saying out loud to myself, ‘What do you think you’re doing? You know you don’t want the result of what you’re doing,’ but I would just keep on going. I don’t know who that is in my head who does that to me.”

I replied, “It’s your inner rat,” because binge eating appears to be a common mammalian response to starvation. Scientists can cause normal-weight rats to binge by alternating food deprivation with access to tasty food, like Count Chocula cereal. Under these conditions (similar to intermittent-starvation diets like the 5:2 program, in which participants eat very little two days per week and don’t worry about calories on the other five), animals eat more of the tasty food and become willing to work harder for it than animals that have it available all the time. For example, rodents develop severe binge eating after repeated cycles of five days of food restriction, then two days of free access to Oreo cookies. Four days later, after regaining their lost weight, they’re given a brief stressor, such as foot shock or being able to see and smell Nutella but not eat it for fifteen minutes. After this treatment, these animals eat twice as much of the Oreos as animals who received the stressor alone. Just a small taste of Oreos can trigger deprived animals to binge on their regular chow if nothing else is available.

Researchers have identified changes in the brain’s dopamine system and other neurotransmitters, which probably change the way that these animals respond to rewards. As in people, the outcomes of these treatments among rats are individually variable, with some animals completely unaffected. Both genetics and early life experiences seem to underlie these differences in vulnerability.

For an animal in the wild without enough food to maintain its body weight, the top priority is getting more. The resulting brain changes reflect that need, increasing the intensity of the animal’s motivation to seek out and eat food. In another set of experiments, adult rats were food restricted until they lost 20 percent of their body weight and then maintained at that weight, which required them to eat less than 70 percent of their normal calorie allotment. These food-restricted rats showed stronger reward responses, not only to food but also to various drugs of abuse. They learned where to find drugs more easily and were more persistent in seeking drugs after they were no longer available. Food restriction also seemed to make sugar water act more like a drug of abuse in their brains.

This research suggests that some food experiences may lead to changes in the brain that make overeating easier, and that repeated dieting might make such changes more likely. That conclusion does not mean, however, that most obese people are food addicts or that addiction to junk food is the main cause of the recent rise in obesity. Most obese people do not show addiction-like brain responses to food and are not binge eaters.

Binge-eating disorder, which occurs in people of all weights, is probably the closest parallel to addictive behavior around food. A key characteristic of addiction is that addicts continue to want something that they no longer like. Binge eaters continue to eat when they’re not enjoying it, despite negative consequences and often triggered by stress, similar to the way addicts take drugs. People with binge-eating disorder are susceptible to other addictions and are more likely to have relatives with drug addiction, suggesting a shared genetic vulnerability. Successful treatment of binge eating may lead to weight loss if the disorder has maintained the person’s weight above its defended range. Other recovered binge eaters do not lose weight because their defended range has increased as a consequence of repeated overeating.

When I gave up dieting, I wanted to remove the constant drain on my willpower and stop wasting effort on failed attempts at weight control. To my surprise, I ended up recovering much more than some free time. Once I gave myself unconditional permission to eat whenever I was hungry, I noticed a major shift in my attitude toward food. Gradually my anxiety about restrictions faded away, and I became more relaxed about leaving food on the plate when I wasn’t hungry, even if it tasted good. In my dieting years, I felt compelled to overeat whenever I was “allowed” to, a compulsion that turned out to be driven by my anticipation of the self-imposed famine to come. When that feeling went away, about six months after I gave up dieting, it was like a stranger had taken over my brain. I no longer feel the need to stock up for the coming famine because I know that I will always allow myself to eat if I’m hungry.

Throughout the first year after I stopped dieting, I worked on noticing when I wanted to eat—and also when I didn’t. In the early stages, I watched myself continuing to eat when I was already uncomfortable, especially in restaurants and at parties, and neglecting to eat when I was ravenous because that felt virtuous, when I could manage it. Over months, I learned to sense and respond to my body’s hunger and fullness cues. My weight stabilized, and I now enjoy food more, while worrying about it less. With practice, controlled eaters can become mindful eaters, as my experience shows. The transition requires time and commitment, but the potential reward is enormous for people whose food has always come with a side order of guilt or shame.

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In conclusion, one needs to change your lifestyle, eat what is right every day, eat regularly and ensure a low carb, minimum starch and one fruit a day lifestyle change. Do not pick up extra after a diet, in other words, don’t diet, eat right!!

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