In our weight-obsessed culture, it’s common to disparage the fat in our bodies. But body fat is a highly specialized organ, critically important for health and longevity.

Among its many functions, fat surrounds and cushions vital organs like the kidneys and insulates us against the cold. Body fat also signifies health, conferring beauty when distributed in the right amounts and locations. But critically, fat is our fuel tank — a strategic calorie reserve to protect against starvation.

Here are a few more things you may not know about body fat:

1. For our ancestors, the key to survival was body fat.

Compared to other species our size, humans have an exceptionally large brain that requires an enormous amount of calories. The metabolic demands of the brain are so great that, under resting conditions, it uses about one of every three calories we consume.

This calorie requirement is absolute. Any interruption would cause immediate loss of consciousness, rapidly followed by seizure, coma, and death. That’s a problem, because until very recently in human history, access to calories had always been unpredictable.

ADVERTISEMENT

Our ancestors faced extended periods of deprivation when a hunt or a staple food crop failed, during harsh winters, or when venturing across an ocean. The key to their survival was body fat.

2. In the absence of body fat, a muscular man would waste away in days without eating.

If we go for more than a few hours without eating, the body must rely on stored fuels for energy, and these come in three basic types: carbohydrate, protein, and fat. The body stores accessible carbohydrate in the liver and protein in muscle, but these are in dilute forms, surrounded by lots of water.

In contrast, stored fat is highly concentrated since fat tissue contains very little water. Plus, pure carbohydrate and protein have less than half the calories of pure fat, making them relatively weak sources of energy. In the absence of body fat, even a muscular man would waste away in days without eating, whereas a majority of adults have enough body fat to survive many weeks.

3. Fat cells are crucial to bodily functions.

And these fat cells aren’t just inert storage depots. Fat cells actively take up excess calories soon after meals and release them in a controlled fashion at other times, according to the body’s needs. Fat tissue also responds to and emits a multitude of chemical signals and neural messages, helping fine-tune our metabolism and immune system.

4. When fat cells malfunction, big problems follow.

The underlying issue in obesity isn’t having too many calories in the body; it’s not having enough in the right place. High insulin levels — caused by our modern processed diet and other influences — have programmed fat cells to take in and store too many calories, leaving too few for the rest of the body.

So when we get hungry, our metabolisms slow down. Eventually, fat tissue develops chronic inflammation, setting the stage for diabetes and heart disease.

Cutting back calories on conventional diets doesn’t solve the fundamental problem: “hungry fat” stuck in calorie-storage overdrive. The best way to calm down fat cells is a higher-fat diet, with the right balance of protein and natural, slow-digesting carbohydrates.

This approach aims to “reprogram” fat cells by lowering insulin levels. When this happens, fat cells release their excess calories back into the body, resulting in decreased hunger and a faster metabolism. A typical day of eating in this manner would include a mix of protein sources like beans, meat, or fish, paired with vegetables like kale, avocado, and salad greens.

Adapted from an excerpt from the book ALWAYS HUNGRY? by David S. Ludwig, M.D., Ph.D. Copyright © 2016 by David S. Ludwig, M.D., Ph.D. Reprinted by permission of Grand Central Publishing. All rights reserved.

Photo credit: iStock


Explore More