Reasons Why it is Not True That Fasting Puts You in "Starvation Mode"

Reasons Why it is Not True That Fasting Puts You in “Starvation Mode”

Starvation mode is the mysterious bogeyman always raised to scare us away from missing even a single meal.

Why? Is it so bad to skip a meal?

Let’s get some perspective here.

Assuming we eat three meals per day, over one year, that’s a little over a thousand meals.

To think that fasting for one day, skipping three meals of the one thousand, will somehow cause irreparable harm is simply absurd.

The idea of “starvation mode” refers to the notion that our metabolism decreases severely and our bodies “shut down” in response to fasting.

We can test this notion by looking at the basal metabolic rate (BMR).

The basal metabolic rate (BMR) measures the amount of energy that our body burns to function normally to keep the lungs breathing, brain functioning, heart pumping, kidneys, liver, and digestive system all working, and so on.

Most of the calories we spend each day are not used for exercise but for these basic functions.

The BMR is not a fixed number but increases or decreases up to 40 percent in response to many variables.

Daily caloric reduction has been well-documented to cause a dramatic reduction in BMR.

In studies with a baseline daily calorie consumption of approximately 2500 calories per day, reducing calories consumed to approximately 1500 calories a day for a long period will result in a 25 to 30 percent reduction in BMR.

On the other hand, overfeeding studies, where subjects are asked to deliberately eat more than they normally do, cause an increase in BMR.

Reduced metabolism makes us generally cold, tired, hungry, and less energetic our bodies are essentially conserving energy by not burning calories to keep us warm and moving.

From a weight standpoint, reduced metabolism is a double curse.

First, we feel lousy while dieting.

Even worse, because we’re burning fewer calories per day, it’s both harder to lose weight and much easier to gain weight back after we’ve lost it.

This is the main problem with most caloric-reduction diets.

Suppose you normally eat 2000 calories a day and cut back to only 1500.

Your body cannot run a deficit indefinitely it will eventually run out of fat to burn so it plans and decreases your energy expenditure.

The result is a decreased BMR.

This has been proven repeatedly by experiments over the last century

Because of this well-known “starvation mode” effect of daily caloric restriction, many people assume that fasting will result in a similar but more severe decrease in BMR.

Luckily, this does not happen.

If short-term fasting dropped our metabolism, humans as a species would not likely have survived.

Consider the situation of repeated feast/famine cycles.

During long winters back in the Stone Age era, there were many days when no food was available.

After the first episode, you would be severely weakened as your metabolism falls.

After several repeated episodes, you would be so weak that you would be unable to get hunt or gather food, making you even weaker.

This is a vicious cycle that the human species would not have survived.

Our bodies do not shut down in response to short-term fasting.

Metabolism moves up, not down, during fasting.

This makes sense from a survival standpoint.

If we do not eat, our bodies use our stored energy as fuel so that we can find more food.

Humans have not evolved to require three meals a day, every day.

When food intake goes to zero (fasting), our body obviously cannot take BMR down to zero we have to burn some calories just to stay alive.

Instead, hormones allow the body to switch energy sources from food to body fat.

After all, that is precisely why we carry body fat to be used for food when no food is available.

It’s not there for looks.

By “feeding” on our fat, we significantly increase the availability of “food,” and an increase matches this in energy expenditure.

Studies demonstrate this phenomenon.

In one, fasting every other day for twenty-two days resulted in no measurable decrease in BMR.

There was no starvation mode.

Fat oxidation fat burning increased 58 percent, from 64 g/day to 101 g/day.

Carbohydrate oxidation decreased 53 percent, from 175 g/day to 81 g/day.

This means that the body has started to switch over from burning sugar to burning fat, with no overall drop in energy.

In another study, four days of continuous fasting they increased BMR by 12 percent.

Levels of the neurotransmitter norepinephrine (noradrenaline), which prepares the body for action, increased by 117 percent, keeping energy levels high.

Fatty acids in the bloodstream increased by over 370 percent as the body switched from burning food to burning stored fats.