Once again, it's about hormones. At night your insulin sensitivity decreases, meaning your body must release more insulin than usual to put any carbohydrates you eat at night to use in the body. And by now you know that higher insulin levels can decrease fat-burning and enhance fat storage. In addition, the body naturally produces a fat-liberating hormone called growth hormone within the initial 90 minutes of sleep.
If you're among the 30% of Americans who sleep less than six hours a night, here's one simple way to whittle your waistline: catch more Zs. A 16-year study of almost 70,000 women found that those who slept five hours or less a night were 30% more likely to gain 30 or more pounds than those who slept 7 hours. The National Institutes of Health suggest adults sleep seven to eight hours a night.
There's no way around the fact that, when it comes to burning more fat, you have to work at it. There is no magic exercise, workout, or pill that will do the job for you. The good news is that it doesn't take much activity to push the body into that fat burning mode. Try incorporating some type of activity every day, even if it's just a quick walk, and build on that over time as it becomes more of a routine. Do that and you're on the way to burning more fat.
“Speed is key—move, walk, or run a little faster and you’ll burn more total calories,” says Kravitz. In fact, changing up your walking pace quickly and frequently can help you melt up to 20% more calories, compared with maintaining a constant speed, according to a 2015 study from The Ohio State University. Try speeding up for 30 seconds, then walking at a comfy pace for three minutes.
Another thing that messes with circadian rhythms? The blue light of digital devices. “We have seen increasing scientific evidence that the more you use devices, the higher your risk of obesity,” says Gillespie. The reason is twofold: One, the more time you spend in front of a screen, the less time you’re running around and playing. But also, experts believe, the blue light these devices emit can disrupt your internal clock. One study found that using a blue light-emitting device before bed delayed the release of melatonin, a hormone responsible for sleep, and the effect carried over to the following night as well.

While the Duke study found no added benefit to resistance training (aka weight or strength training) when it comes to belly fat, a 2014 study from a Harvard University team found otherwise. Twenty minutes of weights a day was linked to less of an increase in belly fat (particularly for older men). “Engaging in resistance training or, ideally, combining it with aerobic exercise could help older adults lessen abdominal fat while increasing or preserving muscle mass," said the paper’s lead author Rania Mekary.

Unintentional weight loss can occur because of an inadequately nutritious diet relative to a person's energy needs (generally called malnutrition). Disease processes, changes in metabolism, hormonal changes, medications or other treatments, disease- or treatment-related dietary changes, or reduced appetite associated with a disease or treatment can also cause unintentional weight loss.[26][27][28][32][33][34] Poor nutrient utilization can lead to weight loss, and can be caused by fistulae in the gastrointestinal tract, diarrhea, drug-nutrient interaction, enzyme depletion and muscle atrophy.[28]


The prevailing formula for a long time on how much fat you’re going to burn was calories in minus calories out, based on your basal metabolic rate (BMR) and exercise efforts, explains strength and performance specialist Joel Seedman, Ph.D., owner of Advanced Human Performance in Atlanta. But with all the different biochemical reactions in the body, hormonal response, and endocrine function, there are an infinite number of factors that can affect how your body is storing and breaking down calories.
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