Browse evidence-based analysis of health-related claims and assertions
Eating a lot of sugar with fructose for weeks doesn’t make your body burn fewer calories at rest — most studies show no change, and only one study saw a small drop under unusual conditions.
Descriptive
When you eat fructose (like in soda), your body burns more calories digesting it than when you eat the same amount of sugar from glucose (like in bread), because your liver has to work harder to turn fructose into usable energy.
Mechanistic
Doing fatmax training helps you lose fat and gain a little muscle, even if you don’t change what you eat.
Causal
When you train at a moderate pace designed to burn fat, your body learns to use less sugar and more fat for energy during workouts.
Fasting for 16 hours a day doesn’t make your body get better at burning fat during exercise any more than just doing the exercise alone.
Eating a small sugary snack before your workout might make it harder for your body to get better at burning fat during exercise, even if you fast the rest of the day.
Doing moderate exercise at a specific heart rate for 8 weeks helps your body get better at burning fat while working out, no matter if you eat before or not.
After eating whole pea flour for a month, the body burned slightly more fat from a labeled oil during the hours after the meal than after eating the processed pea flour.
After eating this pea flour daily for a month, the body seemed to burn slightly less sugar from food for energy, though the difference wasn’t strong enough to be certain.
After eating this high-fiber pea flour for a month, the body used less of the meal’s energy to generate heat, meaning more energy might be stored instead of burned off.
Even though your body burns more fat when you exercise before eating, the amount of fat in your blood doesn’t go up — so the extra fat burning must be happening inside your muscles, not because more fat is being released from fat cells.
Whether you're fit or out of shape, male or female, young or older, working out before breakfast still burns more fat than after eating — as long as you're not sprinting at max effort.
Quantitative
Whether you exercise before or after eating, the amount of fat floating in your blood doesn’t change much during the workout — so the extra fat burning when fasting must be happening inside the muscles, not from more fat being released.
If you eat before working out, your blood sugar and insulin levels spike more during exercise than if you work out on an empty stomach.
Working out before eating breakfast burns about 3 grams more fat than working out after eating, because your body has to use stored fat for energy when you haven’t eaten.
This computer model says if you want to create the least possible disorder in your body, you should exercise as little as possible — but still enough to stay healthy.
The more you move and exercise, the more disorder your body creates from using energy — at least according to this computer model.
A computer model based on how much energy the body uses from food predicts how long people will live — and its predictions are very close to real-life death rates in the U.S.
As people age, their bodies create less disorder (called entropy) from eating and moving, and babies create about three times more of this disorder than older adults.
Taking this supplement for 12 weeks doesn’t make people lose body fat or burn more calories at rest — even though it changes how their muscles use fuel.
After eating a fatty meal, people who took this supplement had lower levels of fat in their blood than those who took a placebo, suggesting it helps the body clear fat from the bloodstream faster.
Even though this supplement helps muscles burn more fat and make more energy, it doesn’t help the body use insulin better to control blood sugar in overweight or obese people.
After taking this supplement combo for 12 weeks, overweight and obese people burn more fat and less sugar for energy, even after eating a fatty meal.
Taking this specific combination of green tea and grape-derived supplements for 12 weeks helps the muscle cells in overweight and obese people make more energy, like upgrading their internal batteries.