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April 7 - May 23, 2020
Adipose tissue is the major energy storage site of the body, and it has an almost unlimited capacity. When you eat more calories than you burn, the excess calories are primarily shunted into your adipose tissue.
When your calorie intake increases, your body weight increases, and this extra tissue burns calories.14 Gradually, as your body enlarges, your calorie expenditure comes to match your extra calorie intake, and you reach a weight plateau.
calories infused into the small intestine increase dopamine levels in the ventral striatum, and the more calories they infuse, the more dopamine spikes.
buffet effect. We tend to overeat spectacularly at buffets, despite the fact that the food isn’t always the crème de la crème.54 At a buffet, we don’t have the opportunity to habituate to any particular food, because every few bites, we’re eating something new.
Sensory-specific satiety also helps explain why we’re happy to eat dessert even after a large meal.
A number of other studies have confirmed that marijuana increases food intake,
Don’t make it too easy for yourself to eat food throughout the day. Even effort barriers as small as having to open a cabinet, twist off a lid, peel an orange, or shell nuts can make the difference between eating the right amount and overeating.
Participants with candy bowls on their desks ate an average of nine Kisses per day. Those with candy bowls in their desk drawers ate six Kisses per day, and those who had to hike all the way across the room only ate four Kisses.
This phenomenon, where a person keeps performing an action even after it’s no longer useful, is called perseveration, and it often results from OFC damage.82 One common and striking consequence of OFC damage is overeating and weight gain.
Increasing dopamine levels using amphetamine makes people more willing to work for rewards, even if the reward is small or uncertain. Dopamine turns us into go-getters.
As soon as you see that bar of chocolate in the candy aisle, your dopamine level begins to spike. This burst of dopamine energizes you to grasp the chocolate and put it into your cart. If you had seen frozen green beans instead, you would have had a much smaller dopamine burst,
Multiple studies have confirmed that people who steeply discount the value of future rewards are more likely to have obesity. They’re also more likely to be addicted to illegal drugs, alcohol, or cigarettes; more likely to gamble; and more likely to carry credit card debt.86 In essence, these are all examples of pursuing immediate rewards without much regard for future consequences.
He reported that the gene codes for a small protein hormone that’s secreted by fat tissue and circulates in the blood. Friedman named this hormone leptin, after the Greek word leptos, meaning “thin.”
Before weight loss, you might have been able to stroll by the ice cream aisle without any problem, but after weight loss, the temptation to buy and eat ice cream can be overwhelming. In effect, substantial weight loss triggers a starvation response, whether a person is lean, overweight, or obese—and this response continues until the fat comes back.
Why aren’t we all taking leptin to lose weight? It turns out that people with garden-variety obesity—as opposed to obesity caused by a rare genetic mutation—already have high levels of leptin.
The leptin system defends vigorously against weight loss, but not so vigorously against weight gain.
once a person develops obesity, it becomes a self-sustaining state, and the person has to overeat to feel the same satisfaction that a lean person feels after eating a smaller meal.
On the bland diet, the starvation response never kicked in. Cabanac concluded that diet palatability influences the set point of the lipostat in humans.
calorie-dense, highly rewarding food may favor overeating and weight gain not just because we passively overeat it but also because it turns up the set point of the lipostat.
focusing the diet on less rewarding foods may make it easier to lose weight and maintain weight loss because the lipostat doesn’t fight it as vigorously.
exercise helps preserve muscle mass during weight loss. Although slow progress on the scale may be frustrating, changes in the mirror and in health as a result of exercise can be better than what the scale suggests.108
In fact, many people report that low-carbohydrate diets help them curb their appetite and cravings, and the research backs this up. When people go on a low-carbohydrate diet, their spontaneous calorie intake drops substantially—even though they usually aren’t making any deliberate effort to eat fewer calories.
leptin controls food intake (in part) by reducing NPY levels in the brain.
While we already have the technical ability to genetically engineer humans, and probably directly manipulate the brain circuits that control eating, we don’t currently consider it ethical. And there are many good reasons for this, one of which is that we haven’t yet demonstrated the safety of this technology.
We overeat because we’re surrounded by seductive, calorie-dense food that’s a great deal. The food’s high reward value increases the set point of the lipostat, though not necessarily permanently, and this further facilitates overeating. At the same time, overeating itself spikes leptin levels and injures the hypothalamus by a mechanism we have yet to nail down (likely involving diet quality in addition to quantity). These two simultaneous hits cause the hypothalamus to lose sensitivity to the leptin hormone, meaning that it requires more leptin, and therefore more body fat, to hold off the
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The brain stem is the most ancient part of the brain, evolutionarily speaking, and it tends to govern deeply instinctual, nonconscious functions, such as digestion, breathing, and basic movement patterns
we now believe the brain stem is the primary brain region that directly regulates meal-to-meal satiety, while leptin and the hypothalamus primarily regulate long-term energy balance and adiposity.
Fruit, meat, and beans tended to have a high satiety index. Plain potatoes were off the charts—far more filling than any other food. Holt and colleagues noted that “simple ‘whole’ foods such as the fruits, potatoes, steak and fish were the most satiating of all foods tested.”
The more fat it contained, the less filling it was per calorie. People often find this counterintuitive, because when they eat high-fat foods, they feel extremely full.
If your goal is to eat fewer calories without going hungry, high-satiety foods will help. These are items that have some combination of low calorie density, moderate palatability, high protein, and/or high fiber, such as beans, lentils, fresh fruit, vegetables, potatoes and sweet potatoes, fresh meat and seafood, oatmeal, avocados, yogurt, and eggs.
Genes also explain that friend of yours who seems to eat a lot of food, never exercises, and yet remains lean.
Identical twins tended to gain the same amount of weight and fat as each other, while unrelated subjects had more divergent responses. Furthermore, not only did twins gain a similar amount of fat, they even gained it in the same places.
the primary reason some people readily burn off excess calories is that they ramp up a form of calorie burning called “non-exercise activity thermogenesis” (NEAT). NEAT is basically a fancy term for fidgeting. When certain people overeat, their brains boost calorie expenditure by making them fidget, change posture frequently, and make other small movements throughout the day. It
A few lucky people are so genetically resistant to obesity that they’re unlikely to develop it under any circumstances. A few others are so genetically susceptible that they may carry excess fat even in a very healthy environment. For the rest us, the environment in which we find ourselves has a major impact on our weight.
sleep restriction increases food intake.
people who short themselves on sleep may not even be aware of how poorly they’re performing.
Astute readers may note that when you sleep less, it also increases your calorie expenditure, because your metabolic rate is higher during wakefulness than during sleep. St-Onge and her team have shown that limiting sleep to four hours a night does indeed increase calorie expenditure, but only by about 100 Calories per day. Since her sleep-deprived volunteers ate nearly 300 excess Calories daily, that still leaves 200 Calories to accumulate around their midsections at the end of the day
Although this remains to be tested scientifically, it’s possible that naturally short sleepers get the same amount of benefit in, say, six hours, that long sleepers get in nine hours. If true, this would suggest that what harms us isn’t necessarily short sleep itself, but rather sleeping less than each of us needs as an individual.
pulling an all-nighter causes people to become less concerned about potential losses and more attracted to potential gains—basically, they become risk takers.
“When you have inadequate sleep,” explains Pardi, “you’re probably less likely to live in accordance with your own health goals. You’re less likely to get into bed on time, you’re less likely to go to the gym, and you’re less likely to have your eating behaviors align with your long-term health goals.”
Your body’s thirty-seven trillion cells don’t get the message that it’s nighttime until you turn out the lights—several hours after the sun goes down. This pushes your biological wake-sleep cycle back by a few hours relative to the day-night cycle of the sun, desynchronizing the two. When it’s time to go to sleep, your body isn’t ready yet, and it also isn’t ready when it’s time to get up.
Rotating shift work is associated with an alarming array of health problems, including obesity, type 2 diabetes, cancer, and cardiovascular disease. The longer a person works a rotating shift, the more likely they are to gain weight and become ill.
