Browse evidence-based analysis of health-related claims and assertions
Eating certain types of fiber may help lower blood sugar in people with type 2 diabetes by feeding good gut bacteria, but it doesn’t work the same for everyone, especially if they’re already taking metformin.
Quantitative
Taking certain good bacteria supplements may slightly lower blood sugar and HbA1c in people with type 2 diabetes, but the effect isn't the same for everyone and depends on the type and amount of bacteria taken.
An imbalance in gut bacteria may cause the gut to leak toxins into the body, triggering inflammation and making it harder for the body to use insulin properly in people with type 2 diabetes.
Mechanistic
Even though they were sweating a lot in the scorching desert, the hunters didn’t lose so much water that they were at risk of dying from dehydration.
Descriptive
People who hunt by running all day in the desert burn a lot of calories and lose a lot of water—but not so much that they get dangerously dehydrated, similar to other desert-dwelling hunter-gatherers.
People didn’t need to run the whole time to catch antelopes—sometimes they just walked, especially if the animal was already hurt.
Even in extreme desert heat, humans didn’t overheat while chasing antelopes, but the antelopes did overheat and collapsed from heat stress.
People running after antelopes in the desert for hours got way more energy from the hunt than other ancient food-gathering methods, making it a very efficient way to get food.
The hunger hormone ghrelin doesn’t seem to affect how the body burns fat vs. carbs after eating, how active someone is, how fit they are, or their eating habits like restraint or hunger feelings.
Correlational
Women with more ghrelin — the hunger hormone — actually eat less each day, which seems surprising but was observed in this group.
Women with more of the hunger hormone ghrelin tend to burn fewer calories at rest and after eating, even when you account for their body size and insulin levels.
Eating sugar before a workout makes your body burn more sugar during the workout—instead of fat.
Causal
After a workout, your body burns more calories for a while if you ate protein before you started—more than if you ate sugar.
Eating protein before a workout doesn’t stop your body from burning fat like eating sugar does—so if you want to burn fat while exercising, protein is safer than carbs.
Eating protein before a workout makes your body keep burning more calories for a while after you stop—more than if you ate sugar instead.
If overweight people drink more than a liter of water a day while eating less, they lose more weight — even if they’re not eating fewer calories overall — possibly because their insulin levels drop and their body burns fat better.
Just drinking more water won’t help you lose weight unless you actually stop drinking sugary drinks — and if you only drink a little extra water, it won’t make a difference.
If kids or overweight adults switch from soda or juice to water without changing what they eat, they tend to gain less weight over time — but if they’re on a strict diet, water doesn’t help much.
For people who are overweight, drinking a glass of water on an empty stomach can slightly boost calorie burning, but this doesn’t happen in people with normal weight.
When you drink water instead of sugary drinks while resting or doing light exercise, your body burns more fat because sugar in drinks tells your body to stop burning fat.
If you drink water instead of soda, juice, or milk with your meals, you tend to eat less food overall, which can help you take in fewer calories.
When people eat high-protein, low-carb ultra-processed foods, their bodies burn more fat and protein for energy and store less fat, compared to when they eat normal-protein ultra-processed foods.
When people eat high-protein, low-carb ultra-processed foods, their bodies release more hormones that tell them they’re full (PYY and glucagon) and less of the hunger hormone (ghrelin), which may explain why they eat less.
Even though people still ate more calories than they burned, eating high-protein, low-carb ultra-processed foods made them much less likely to store excess energy as fat compared to normal-protein ultra-processed foods.