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The Harms of Chronic Calorie Restriction

Move more, eat less, we've all heard that this is the only way to lose weight. But today we are going to debunk the calories in calories out method and discuss the harms of chronic calorie restriction long-term. Does calorie restriction work in the short term? For some people yes, it is short-term. But long-term people end up gaining back their weight and then some. And for women it's not a short-term fix, it becomes an obsessive yo-yo diet train that follows them for the rest of their lives.

In recent years, studies overwhelmingly have shown that calorie restriction does not work, yet many still believe it's the only way to lose weight. Let’s review some reasons why calorie restriction doesn't work…and then look at what does.

1. Calorie restriction can put your body in “Starvation Mode”

Calorie-restricted diets create a cascade of effects throughout the body that lead to metabolic inefficiency, also known as metabolic adaptation. The greater the calorie deficit and the more chronic it becomes, the greater the inefficiency within the body. Multiple systems in the body are fighting to return to and maintain that higher weight that you are so desperately trying to bring down. Your body does this by reducing energy output, calories burned, and down-regulating essential hormone pathways. This down-regulation of metabolism and adaption to reduced nutrients are referred to as “starvation mode.”

As noted above, as a person loses weight, their metabolic rate actually slows down. Smaller bodies don’t have to work as hard to function as they did at a greater weight. And contrary to what you might think, as weight is lost, appetite actually increases over the former baseline. So, not only does someone focusing on calories have to remain at a permanently lower caloric intake to maintain a now lighter weight, they have to do so even hungrier than before.

2. The Harms of Chronic Calorie Restriction Lead to Yo-Yo Dieting

As mentioned above, calorie restriction slows an individual’s metabolic rate. When the metabolic rate is slowed, a person has less fuel available for the many functions the body requires, leaving the person with less energy and more hunger. Because the body is now operating with less energy, weight loss plateaus. In frustration, most people try to pick back up their previous diet, but this time with a lower metabolic weight. This leads to them regaining their lost weight, and often more. This pattern of losing and gaining weight is known as the yo-yo effect.


3. Caloric Quality vs Caloric Quantity

Whenever we eat anything, our bodies work to break it down, meaning that our metabolic “rate” increases during that period of digestion. The body has to work harder to break down protein than it has to for carbohydrates (which convert to glucose in the body). If the body uses more energy to digest a steak than it does to digest the same number of calories in apples (let alone something like cake), then that makes those calories unequal. Even carbohydrates are digested at different rates, thereby having a different effect on your body and metabolism. Simple carbs like potatoes, pasta, and candy digest quickest, causing more rapid increases in blood sugar. Complex carbs like quinoa or leafy greens take longer for the body to break down, making the impact on blood sugar and insulin steadier and more moderate. Protein takes longer still, driving metabolic rate higher thanks to the thermic effect of food.

4. Hormones

Insulin, leptin, and ghrelin, each of these hormones respond differently to different foods. The simpler the carbohydrate, the more rapidly it’s digested and absorbed, creating a dramatic spike in blood glucose. That spike sets off a chain reaction throughout the body.


Insulin

The digestive system breaks down any digestible (non-fiber) carbs into sugar. That sugar enters the bloodstream and tells the pancreas to release insulin. Insulin then instructs the body to use some of that sugar in the bloodstream as immediate energy, but it tells the rest to be stored as fat throughout the body. For insulin-sensitive people, only a small amount of insulin is necessary to keep this essential process happening. But the more a body is subjected to a hormone, the more resistant it becomes to it. As an individual keeps eating carbohydrates, the body produces more and more insulin, which in turn leads to more and more stored fat.

Fat and protein are different stories. By itself, pure dietary fat has virtually no impact on insulin, whereas protein causes a slow insulin increase over time. However, there are some key features that diminish the impact of protein on potential fat storage. First, there is not as much insulin required at one time (thereby preventing insulin resistance) when eating protein. Second, in healthy non-diabetic people, insulin and glucagon are released after high-protein meals. Glucagon further regulates blood sugar, lessening the impact of insulin. Third, when protein is digested its primary function is to repair and build cells. Digestion breaks down protein into amino acids that are sent throughout the body to perform these necessary functions.

The moral of the story, while protein will elicit an insulin response, 1000 calories of egg whites will not lead to the same fat storage as 1000 calories of bananas.


Ghrelin

In the presence of any food, the hunger hormone ghrelin is temporarily suppressed. After eating simple carbs, however, ghrelin markedly rises after only two hours, and it rises even above where it had been, leaving you hungrier than before. By contrast, when fat is consumed, ghrelin stays low for about four hours and only then begins its more gradual climb. Protein also keeps ghrelin (hunger) low longer than carbohydrates will.

In other words, carb-heavy snacks and meals lead to greater and more constant hunger than an equivalent amount of fat and/or protein. So, calories don’t tell the whole story.


Leptin

Leptin is the hormone of satiety or satisfaction. Eating carbohydrate-heavy meals will release more leptin than fat-heavy or protein-heavy meals will. This seems like a good justification for eating more carbs. But hold on.

Leptin is released from fat cells. So as a body starts gaining more fat, leptin levels continue to climb. This quickly becomes problematic, because as already established, when the body gets too much of a hormone, it becomes resistant to that hormone. In the case of leptin resistance, with so much leptin released from fat cells, the hypothalamus will start to ignore the hormone. The brain then misses the signal to stop eating, which contributes to further weight gain, which leads to even more fat cells releasing leptin, and so on.

Interestingly, while more leptin is not released by eating protein, what it does increase is satiety!

The takeaway? Calorie for calorie, protein leads to increased satiety without the same risk of leptin resistance as carbohydrates.

Now that you’ve seen evidence that calories are not the whole story of weight loss, let’s look at what actually works. Customized nutrition is best when it comes to figuring out what your body needs to be in optimal health.

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