Browse evidence-based analysis of health-related claims and assertions
If you keep your blood sugar and ketone levels in a specific balance for about 3 days, your body switches from burning sugar to burning stored fat and producing ketones for energy instead.
Mechanistic
Eating sardines gives you lots of healthy fats called omega-3s (like DHA and EPA) that calm down inflammation in your body and help protect your muscles from breaking down.
When we don't eat for a while, our insulin levels drop, and this low insulin triggers our cells to clean themselves up through a process called autophagy.
When people fast while eating sardines, their insulin levels drop dramatically, and the fat stored around their internal organs (visceral fat) is the first type of fat their body burns for energy.
Causal
Scientists thought your body mostly burns fat at rest and during easy exercise, but new measurements show your body actually burns a lot of carbohydrate too - around 40-60% of the energy you use.
Going on a low-carb, high-fat diet doesn't make runners slower, even though their muscles store less sugar for energy.
Switching to a low-carb, high-fat diet makes your body burn fat for energy much faster—going from burning 0.50 grams per minute to 1.40 grams per minute in just 5 days—and this effect goes away when you switch back to a high-carb diet.
Quantitative
About 30% of middle-aged competitive athletes eating a typical high-carb, low-fat diet have blood sugar levels that are higher than normal but not quite diabetic. When these athletes switch to a low-carb, high-fat diet, their blood sugar returns to normal levels.
When endurance athletes do high-intensity interval training at very hard effort (over 85% of their maximum oxygen capacity), they burn fat at extremely high rates - about 1.58 grams per minute on average, with some burning over 1.85 grams per minute. These are the highest fat-burning rates ever measured in people.
Athletes who follow low-carb high-fat diets can burn fat much faster during exercise—over 1.5 grams per minute—compared to athletes on regular high-carb diets who only burn 0.3 to 0.6 grams per minute.
When people switch to a low-carb, high-fat diet, their bodies can burn fat for energy during harder workouts that would normally require carbs, whereas on a normal diet this switch happens at easier exercise intensities.
When you exercise for a long time (over 2-3 hours), it's actually having low blood sugar that makes you feel tired and stop exercising—not your muscles running out of stored energy.
Glioblastoma is the deadliest type of brain cancer in adults - even with the best treatments available like surgery, radiation, and chemo, most patients only live about 1-2 years, and almost no one survives for 10 years.
Descriptive
Using a screen that shows muscle activity in real-time while doing a shoulder rotation exercise might help people with rounded shoulders move better and recover faster from injuries.
When someone has rounded shoulders, the back part of their shoulder muscle might work too hard when rotating the shoulder outward. This could throw off the normal muscle balance around the shoulder joint and lead to shoulder problems.
Using a machine that shows muscle activity in real-time while doing shoulder exercises helps people with rounded shoulders activate their back shoulder muscle more than the back part of their shoulder muscle, which is a good thing for shoulder health.
Correlational
When adults with rounded shoulders use a device that shows them their muscle activity in real-time while doing a shoulder rotation exercise, it helps them reduce overactive muscles in the back of the shoulder that cause problems.
When people with rounded shoulders do a shoulder rotation exercise while getting real-time feedback from muscle activity sensors, their infraspinatus muscle works harder compared to doing the exercise without feedback.
Using proper form with lighter weights can build muscle just as well as using heavy weights with sloppy form, and it might even be safer and more efficient.
If you do an exercise in a way that makes other muscles help out instead of focusing on the muscles you're trying to work, you won't get as good of a workout for those target muscles.
When you do strength training with your muscles stretched out (like in a full squat versus a half squat), you tend to build more muscle. But this works better for people who are new to training than for people who already lift weights regularly. Scientists may have originally overstated how big this difference really is because studies showing bigger effects get published more often than studies showing smaller effects.
When nutrition and exercise scientists disagree, it's usually about what their study results mean, not about what the results actually show.
Thinking really hard about a specific muscle while exercising won't make that muscle work harder, unless you actually change how you're doing the exercise.
Scientists are having trouble replicating exercise science studies because they keep misunderstanding 'no significant result' as 'the original finding was wrong' - when really, the new studies often show the same effect size, they just didn't hit the magic statistical number to prove it.