Browse evidence-based analysis of health-related claims and assertions
If you lift the same total amount of weight, lifting heavier weights (80% or more of your max) makes you stronger in a single big lift than lifting lighter weights—but lifting very light weights and light weights (under 60%) give you about the same strength gains.
Quantitative
Eating lots of colorful veggies, berries, nuts, and fish may help sperm health by giving the body more natural defenses against damage.
Correlational
Men who ate fewer carbs (especially sugar and white bread) had less damage to their sperm DNA, possibly because high sugar intake increases harmful stress in the body.
Eating mostly organic food may help protect sperm DNA and boost testosterone by reducing exposure to pesticides and increasing natural antioxidants.
Men who ate a healthy, organic, low-carb diet for 3 months had much less damage to the DNA in their sperm, which could make it easier to conceive.
Men who ate mostly organic, low-carb Mediterranean food (lots of veggies, nuts, fish, and no junk food) for 3 months had much higher levels of the male hormone testosterone.
When you eat very few carbs, your body burns up the protein you eat for energy instead of using it to repair and build muscle.
Descriptive
When your muscles don’t have enough stored sugar (glycogen), you can’t sprint as fast or go as long during all-out efforts like cycling or running hard.
When you eat very few carbs, your body breaks down important muscle-building amino acids instead of using them to grow muscle, making it harder to get stronger from weight training.
People who don’t lift weights regularly burn more sugar from their muscles during a workout than people who lift regularly.
Changing the weight you lift during a workout burns more muscle sugar than lifting the same weight the whole time.
Lifting heavier weights doesn’t necessarily burn more sugar in your muscles—it might actually burn less, possibly because you can’t do as many reps.
The longer you spend lifting weights, the more sugar your muscles use up.
The more sets you do when lifting weights, the more sugar your muscles burn through.
Lifting weights once can use up a lot of the sugar stored in your thigh muscles, which your body needs for energy during hard exercise.
Whether you eat a lot of carbs or very few, as long as you’re eating the same total calories and protein, you’ll gain the same amount of strength and muscle over several months of weightlifting.
If you're doing a really long, intense workout or two hard sessions in one day, eating carbs might help you lift more—but only if you were hungry or hadn't eaten, not if you're eating the same number of calories from other foods.
If you want to burn more fat during a 30-minute workout, steady running on a treadmill burns more fat than high-intensity hydraulic training, weightlifting, or biking at the same intensity.
When doing a high-intensity workout on a hydraulic machine, your body burns more sugar (carbs) for energy than when you lift weights, run, or bike at the same time.
People feel like they’re working much harder during a 30-minute hydraulic machine HIIT workout than during weightlifting, running, or biking, even though they’re resting part of the time.
When doing a 30-minute workout on a hydraulic machine with short bursts of maximum effort, your heart beats much faster than when you're lifting weights, running, or biking at a steady pace.
Doing a 30-minute workout on a hydraulic machine with short bursts of all-out effort burns more calories than the same amount of time lifting weights, running on a treadmill, or riding a bike.
After doing weight lifting or short bursts of intense cardio, your body keeps burning more calories for hours afterward than it does after a long, slow jog—even if you burned the same total calories during each workout.
Both men and women burn more fat after heavy weights before cardio, even though women tend to breathe harder during the cardio than men do.