Browse evidence-based analysis of health-related claims and assertions
People with more active brown fat burn an extra 2% of their meal’s calories after eating carbs — which could add up to a few hundred extra calories burned per day over time.
Quantitative
Your brown fat only helps burn calories after you eat carbs — not after you eat protein or fat — which means it’s picky about what food it helps you burn.
Correlational
Eating a high-protein meal burns more calories than eating carbs or fat, but this doesn’t depend on how active your brown fat is — your body must be using other ways to burn those extra calories.
Men and women gain muscle at about the same relative rate when they train the same way—women just start with less muscle, so they gain less in absolute numbers.
Descriptive
New lifters can expect to gain about 1–2 kg of muscle in the first few months, but after that, gains slow down dramatically—most people only add 2–4 kg per year even with years of training.
Muscles don’t grow bigger by filling up with water or glycogen—they grow by adding more of the actual contractile parts that make them strong.
Mechanistic
The burning feeling and muscle pump you get during a workout don’t make your muscles grow—those are just side effects, not the reason your muscles get bigger.
Causal
The spike in 'muscle-building hormones' after a workout doesn’t make your muscles grow bigger—your muscles grow from lifting weights, not from hormone surges.
Lifting weights makes your muscles grow mainly because of the physical force you create when you contract your muscles—not because of hormones, burning sensations, or muscle pumps.
Your body burns the most calories after eating protein, fewer after carbs, and the least after fat — which is why high-protein diets are often used for weight loss.
Eating a fatty meal doesn’t make your body burn many extra calories, and your brown fat doesn’t seem to play any role in that process.
Eating a high-protein meal makes your body burn more calories afterward than eating carbs or fat, but this boost isn't linked to your brown fat — something else is responsible.
After eating a carb-heavy meal, people with more active brown fat burn about twice as much extra energy as people with less active brown fat, which might help with managing body weight.
Leg extensions make the whole front of your thigh muscle grow evenly, while squats mainly make the middle part of a different thigh muscle grow.
Even if you work out the same amount and intensity, what exercise you pick can change which part of your muscle gets bigger.
Different leg exercises make different parts of your thigh muscles grow bigger—leg extensions grow all parts of one muscle, while squats mainly grow the middle part of another.
Even when people get tired, they still mostly stick to the tempo they planned—so training with specific timing (like slow lowers) is realistic and doable.
You can still build muscle and stay strong with lighter weights if you slow down the movement—this is especially helpful for seniors, injured people, or athletes taking a break from heavy lifting.
Rapidly pushing up a weight (like exploding upward in a squat) may make you stronger and faster than lifting the same weight slowly.
Slowing down the lowering part of a lift (like slowly lowering a dumbbell) makes your muscles more damaged and triggers more repair and growth than quickly lowering it.
How long your muscles are working during a lift matters just as much as how heavy the weight is for building muscle, burning energy, and improving nerve-muscle control.
Even if you lock your knees at the top of a squat, your thigh muscle still gets less oxygen during the exercise than when you're just standing still — but not as much as if you keep your knees bent.
If you keep your knees bent while squatting (no locking), your thigh muscle gets more oxygen-starved than if you lock your knees at the top — even if you do it for the same amount of time.
When you squat all the way down without locking your knees, your thigh muscle gets more oxygen-deprived than if you stop short and lock your knees — which might help build muscle.