There is a lot of misinformation about how to lose body fat. Many people think calorie counting is a good way to get lean. The problem with this approach is that it doesn’t take hormones into consideration. This is a huge problem because hormones regulate hunger, metabolic rate, food preferences, and energy levels.
This article will explain the complicated relationship between hormones and body composition by taking a look at the role of the most important metabolic hormone: Insulin.
The Relationship Between Hormones & Calories
We know from the first law of thermodynamics that in order to lose body fat, you have to burn more energy than you take in every day. It’s very important that everyone understand that the energy you consume and the energy you burn are dependent variables that impact each other.
For example, the thermic effect of food dictates how much energy your body burns digesting and absorbing that food. When you eat a meal of pure protein, your body will burn 25 percent of the energy supplied in the meal, whereas for fat, it will burn only 0 to 3 percent and for carbs 5 to 15 percent.
Additionally, the composition of your diet from carbs, fat, or protein influences how hungry you are and the amount of calories you’ll eat at subsequent meals. For example, protein foods are very satiating because they trigger the release of gut hormones that decrease hunger. Protein also causes a large elevation in insulin but without a spike in blood sugar. This combination has a hunger-reducing effect.
Finally, how you expend energy influences how hungry you are and what you’ll be most inclined to eat. A very simple example is that when people are motivated to exercise in order to lose fat, they usually aren’t successful because they end up eating more calories afterwards. Scientists think that people have become conditioned to reward themselves with high-calorie foods for physical efforts that they associate with weight loss.
So what does all this have to do with insulin?
Insulin and other metabolic hormones like glucagon, leptin, and ghrelin all affect the interplay between what you eat and how much you burn. If you have good metabolic health and are insulin sensitive (a term that will be described in depth below) it makes it much easier to ensure you are not eating more calories than you burn.
What Insulin Is & Why It Matters
Insulin is a hormone that is secreted by the pancreas. Its main role is to regulate the amount of nutrients circulating in the bloodstream. When you eat a meal, the amount of sugar (glucose) in your blood stream increases.
The pancreas senses the increase in sugar and releases insulin into the blood. Insulin binds with your cells in order to store the glucose either in muscle as glycogen (the energy source for the muscle) or as fat. The body will replenish glycogen first, only storing excess glucose as fat if glycogen stores are topped off. This is one reason that exercise is the holy grail, both for improving insulin sensitivity and for losing body fat.
Sometimes the cells become resistant to insulin, which means they aren’t readily binding to it. When this happens, the body will pump out more insulin to bring blood sugar levels down. This is an essential physiological effect because very high amounts of sugar in the blood can have harmful effects, causing damage to organs, inducing a coma, or potentially leading to death if untreated.
When you have high blood sugar, the pancreas may not be able to keep up anymore. The cells in the pancreas can become damaged. This leads to decreased insulin production. When you have low amounts of insulin and cells that don’t respond to the little insulin that's available, you will have sky high blood sugar levels, which cause a host of acute and long-term health problems including diabetes.
What Causes Insulin Resistance?
Many people will incorrectly answer “refined carbs!” to this question. If only it were that simple.
In reality, a number of interrelated factors contribute to insulin resistance. Studies consistently show that when you have high amounts of free fatty acids in the blood, the cells stop responding properly to insulin. Scientists think this is caused by a couple of different factors:
Eating excess calories. Insulin resistance may actually be a protective mechanism for fat cells that have grown too large so that no more fat will be deposited into them.
Having increased belly fat. Belly fat is the dangerous kind of fat that surrounds the organs and releases chemical signals that keep insulin from effectively binding with cells.
Physical inactivity and low muscle mass. In the body, more glucose is used by muscle than other tissues. Normally, active muscles burn their stored glucose for energy and refill their reserves with glucose taken from the bloodstream, helping to keep blood glucose levels in balance. Additionally, when you train muscle, you automatically increase insulin sensitivity. This is why exercise, particularly intense forms like weight lifting or intervals, can help reverse diabetes.
Stress and elevated cortisol. Cortisol is a hormone that is released in response to both physical and mental stress. It influences your body’s ability to regulate blood sugar. Cortisol will free glucose stores to give you energy to get through a stressful experience. When this happens infrequently it is protective, but when you are under chronic stress and your body is pumping out cortisol and raising blood sugar consistently all day long, insulin also gets elevated. When this happens over and over again, insulin resistance can develop.
Inflammation. Energy excess (eating too many calories on a regular basis) is thought to cause insulin resistance in part by activating inflammatory pathways in the body that inhibit insulin signaling, making cells less sensitive to bind with insulin.
Harmful gut bacteria. The bacteria in your gastrointestinal tract feed off what you eat. Unfortunately, certain strains of bacteria can increase the absorption of calories from the food you eat, increasing your energy intake. These bacteria also activate inflammatory pathways, contributing to insulin resistance and metabolic problems.
How Does Diet Affect Insulin Resistance?
Because low-carb diets are often used as a therapy to treat type 2 diabetes, people often mistakenly think that eating too many carbs is what led to the condition in the first place. This is an error of logic. Although low-carb diets can improve metabolic markers and restore insulin sensitivity, it doesn’t mean that higher carb intake causes insulin resistance.
What is true, on the other hand, is that diets high in refined and processed carbs are well known to spike blood sugar and trigger food intake. Additionally, they are associated with fat gain because they are calorically dense. These foods have a low thermic effect compared to whole carbs or protein and it’s quite possible that consuming them leads people to feel sluggish and unmotivated to move, thereby spontaneously reduce physical activity so that they burn fewer calories over the course of the day.
Insulin Sensitivity Predicts Fat Loss
Which brings us to the most interesting part of this article: Body fat loss.
Emerging research shows that the amount of fat you will lose from a diet is most determined by your insulin health.
For example, a recent trial classified women as “insulin resistant” or “insulin sensitive” and put them on either a low-fat, calorie-restricted diet or a low-carb diet. The low-carb diet didn’t require calorie restriction due to the fact that the women in this group naturally ate much fewer calories than normal. Among the insulin resistant women, only those on the low-carb diet lost any fat. They reduced body fat by an average 2.3 percent.
The women who were classified as insulin sensitive lost roughly the same amount of body fat regardless of whether they were on the low-carb or low-fat diet (the low-carb group lost an average 3.2 percent body fat and the low-fat group lost 2.7 percent, which is not a statistically significant difference).
We can make a few conclusions from this study:
1) If you are insulin resistant, following the traditional “diet” that is calorie restricted but high in carbohydrates will actually undermine your ability to lose body fat.
2) If you are very insulin resistant, cutting carbs a little bit, or playing around with small reductions in your glycemic load probably won’t have any effect. You need a more radical approach to reset your metabolism.
3) People who are sensitive to insulin have a lot more flexibility in the type of diet they use to lose body fat. This suggests that the key is to optimize insulin sensitivity first.
How Can You Improve Insulin Sensitivity?
Pick one or two and make them habits so that they are an easy part of your lifestyle. Chances are with a little improvement in your metabolic health, it will kickstart other healthy behaviors on the list. Good Luck!