Cutting calories and fasting are not the same diet
A doctor argues calorie cutting slows the burn and costs muscle, while fasting lowers insulin in a different way.
The Diary Of A CEO Clips · THIS Is #1 FASTEST Way To BURN Dangerous FatEating a little less every day and eating nothing for stretches may sound like two versions of the same diet, but a doctor who treats patients with belly fat says the body treats them differently.
The difference, he says, starts with insulin. He calls insulin "a storage molecule" that "puts everything away." A person with high insulin, he says, can go on a cruise and come back five to 10 pounds heavier, because that storage signal makes gaining weight easy and losing it hard.
Not eating for a stretch, he says, lowers that signal because you stop stimulating the pancreas, the organ that makes insulin, so insulin levels fall.
Steadily cutting calories, he says, triggers a different response. The body senses the ongoing deficit, the metabolic rate, the speed at which the body burns energy, slows down, and the body breaks down fat and muscle together.
In his account, fasting involves what he calls "a totally different physiology." He argues that fasting is the way to bring insulin down, and he answers no when asked whether fasting and a calorie deficit are the same thing.
That is his claim about how the body responds, not a guarantee for every fast. No fast is fully muscle sparing, and any comparison assumes people eat enough protein when they do eat, keep using their muscles, and do not attempt long fasts without medical supervision.
Questions people ask
Does eating less really slow metabolism?
Yes. Researchers call it metabolic adaptation. When calories stay low for weeks, most people burn fewer calories at rest than before, and part of the lost weight is lean tissue. That is one reason weight loss often stalls and regain is common.
How quickly does insulin fall when I stop eating?
Insulin starts to fall within hours of your last meal, once no new food needs to be stored. It drops fastest when no carbohydrates or protein are coming in, because both stimulate the pancreas. That is why an overnight stretch without food lowers insulin more than grazing on small low calorie meals.
Does fasting burn zero muscle?
No fast is completely muscle sparing, especially very long ones without medical supervision. The claim is comparative: with adequate protein when you do eat, and resistance exercise, short fasts tend to preserve more muscle than continuous severe dieting. Prolonged water fasts should only be done with a doctor involved.