Why Is Sleep So Important to Weight Loss?

When you're short on sleep, it's easy to lean on a large latte to get moving. You might be tempted to skip exercise (too tired), get takeout for dinner, and then turn in late because you're uncomfortably full. If this happens a few times each year, no problem. Trouble is, more than a third of Briton's aren't getting enough sleep regularly. Yet experts agree that getting enough shut-eye is as important to health, well-being, and your weight as diet and exercise.

Your Sleepy Brain

Skimping on sleep sets your brain up to make bad decisions. So it's a little like being drunk. You don't have the mental clarity to make good decisions. Plus, when you're overtired, your brain's reward centers rev up, looking for something that feels good. So while you might be able to squash comfort food cravings when you're well rested, your sleep-deprived brain may have trouble saying no to a second slice of cake.

Research tells the story. A study in the American Journal of Clinical Nutrition found that when people were starved of sleep, late-night snacking increased, and they were more likely to choose high-carb snacks. In another study done at the University of Chicago, sleep-deprived participants chose snacks with twice as much fat as those who slept at least 8 hours. A second study found that sleeping too little prompts people to eat bigger portions of all foods, increasing weight gain. And in a review of 18 studies, researchers found that a lack of sleep led to increased cravings for energy-dense, high-carbohydrate foods. Add it all together, and a sleepy brain appears to crave junk food while also lacking the impulse control to say no.

Sleep and Metabolism

Sleep is like nutrition for the brain. Most people need between 7 and 9 hours each night. Get less than that, and your body will react in ways that lead even the most determined dieter straight to the biscuit tin. Too little sleep triggers a cortisol spike. This stress hormone signals your body to conserve energy to fuel your waking hours. Translation: You're more apt to hang on to fat. Then we have two important hunger hormones, ghrelin, and leptin.

Ghrelin is a hormone released in the stomach that signals hunger in the brain. Levels are high before you eat when the stomach is empty and low after you eat.

Leptin is a hormone released from fat cells. It suppresses hunger and signals fullness in the brain.

When you do not get adequate sleep, the body makes more ghrelin and less leptin, leaving you hungry and increasing your appetite. A study of over 1,000 people found that those who slept for short durations had 14.9% higher ghrelin levels and 15.5% lower leptin levels than those who got adequate sleep.

Sleep deprivation makes you "metabolically groggy," University of Chicago researchers say. Within just 4 days of insufficient ZZZs, your body's ability to process insulin -- a hormone needed to change sugar, starches, and other food into energy -- goes awry. Insulin sensitivity, the researchers found, dropped by more than 30%. When your body doesn't respond properly to insulin, your body has trouble processing fats from your bloodstream, so it ends up storing them as fat. So it's not so much that if you sleep, you'll lose weight, but that too little sleep hampers your metabolism and contributes to weight gain.

Tricks and Tips for a Better Night's Sleep

In today's world, snoozing can be difficult, mainly when all your screens (computers, TVs, mobile phones, tablets) lure you into staying up just a little longer. The basics are pretty simple:

• Shut down your computer, mobile phone, and TV at least an hour before you hit the sack. Save your bedroom for sleep and sex. Think relaxation and release, rather than work or entertainment.

• Create a bedtime ritual. It's not the time to tackle big issues. Instead, take a warm bath, meditate, or read.

• Stick to a schedule, waking up and retiring at the same times every day, even on weekends. Watch what and when you eat. Avoid eating heavy meals and alcohol close to bedtime, which may cause heartburn and make it hard to fall asleep. And steer clear of sugary drinks, tea, coffee, and chocolate after 2 p.m. Caffeine can stay in your system for 5 to 6 hours.

• Turn out the lights. Darkness cues your body to release the natural sleep hormone melatonin, while light suppresses it.