Browse evidence-based analysis of health-related claims and assertions
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.
Causal
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.
Correlational
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.
Mechanistic
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.
Eating ultra-processed foods with more protein and fewer carbs makes your body burn about 130 extra calories per day just to digest and process the food, even if you’re not moving more.
When healthy young people eat ultra-processed foods that are high in protein and low in carbs, they naturally eat about 200 fewer calories per day than when they eat ultra-processed foods with normal protein and carbs—even if both meals taste the same.
How much water someone drinks doesn’t seem to directly affect the level of a key water-regulating hormone in their blood.
People who don’t drink much water may burn slightly fewer calories over the course of a day, especially in populations living in hot, dry climates.
People who drink less water tend to eat less food later, even if they’re not hungry or trying to diet.
Higher levels of a hormone linked to water balance (copeptin) are tied to the body burning less fat and more sugar, even when hydration levels are accounted for.
When people drink less water, their bodies tend to burn more fat and less sugar for energy, even if they’re not trying to lose weight.
Even though people liked the whole-food sandwich more, that didn’t make their body burn more calories — so the calorie-burning difference isn’t because of taste.
The processed sandwich has way less fiber than the whole-food one — about one-third — which might make it easier for your body to digest and burn fewer calories.
Quantitative
Even though your body burns more calories digesting a sandwich made with real ingredients, you don’t feel any fuller than if you ate one made with processed ingredients.
Descriptive
Eating a sandwich made with real bread and real cheese burns almost twice as many calories during digestion as one made with white bread and processed cheese, even if both have the same number of calories.
The studies on these supplements are too messy and unreliable to say for sure if they help overweight kids — we can't trust the results much.
These supplements don't reliably help kids improve their cholesterol or triglyceride levels — the studies show no clear benefit.