“Under normal conditions, humans absorb only about 80% of the nutrients from the food they eat,” says A. Roberto Frisancho, Ph.D., a weight-loss researcher at the University of Michigan. But, he says, when the body is deprived of nourishment, it becomes a super-efficient machine, pulling what nutrients it can from whatever food is consumed. Start eating again normally and your body may not catch up; instead it will continue to store food as fat.
Still not convinced to make sleep a priority? A lack of sleep doesn't only affect how much and which food you eat, but also how it metabolizes that food. Insufficient sleep messes with your metabolism by making your body more insulin resistant—a condition that usually leads to diabetes and weight gain—according to a 2012 study published in the Annals of Internal Medicine. (And, get this, it even changes your fat cells.)

In what is perhaps the biggest buzzkill of all time, sex doesn’t quite count as cardio or burn a significant amount of calories: Women burn about 3.6 per minute. "It’s still a good idea," Dr. Seltzer says, citing the activity’s other benefits, like increasing the output of the neurotransmitters serotonin and dopamine, which naturally reduce food cravings.


The reason we’re suggesting 45 minutes instead of the typical 30 as one of the ways to lose weight is that a Duke University study found that while 30 minutes of daily walking is enough to prevent weight gain in most relatively sedentary people, exercise beyond 30 minutes results in weight and fat loss. Burning an additional 300 calories a day with three miles of brisk walking (45 minutes should do it) could help you lose 30 pounds in a year without even changing how much you’re eating. Here are 20 hidden reasons your diet isn’t working.


Like protein, fiber slows the rate at which your body plows through carb calories so you feel full for longer and maintain steadier blood sugar levels, one reason why research consistently links fiber intake to weight loss. That means fibrous whole grain bread tends to be a better choice than white bread and also explains why fruits, which contain fiber and valuable vitamins in addition to sugar, beat straight-up candy every time.
When Tufts University researchers studied the waistlines and diets of 459 people, they found that even in men of similar age and activity level, those who ate white bread frequently weighed more than those who didn’t. “The calories from white bread and refined grains just seem to settle at the waistline more than calories from other foods,” says Katherine Tucker, Ph.D., the study author.
At the same time, wearing clothes you can actually move in (read: not stilettos and a tiny pencil skirt) to work might help keep you active during the day instead of parked at your desk. A study by the American Council on Exercise found that people took an average of eight percent more steps on days that they wore jeans instead of conventional business clothes. You officially have a health excuse to ask for casual Friday every day.
What happens if you fast for a day? What happens if you don't eat for a day? While most people will feel hungry and possibly tired, there is also a range of other effects. In this article, learn about how the body starts to burn fat for energy and whether fasting for 24 hours can be a good weight loss tool. We also investigate the possible risks. Read now
Sure, ketchup is tasty, but it’s also a serious saboteur when it comes your weight loss efforts. Ketchup is loaded with sugar — up to four grams per tablespoon — and bears little nutritional resemblance to the fruit from which it’s derived. Luckily, swapping out your ketchup for salsa can help you shave off that belly fat fast. Fresh tomatoes, like those used in salsa, are loaded with lycopene, which a study conducted at China Medical University in Taiwan links to reductions in both overall fat and waist circumference. If you like your salsa spicy, all the better; the capsaicin in hot peppers, like jalapeños and chipotles, can boost your metabolism, too.
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