The age-old advice for weight loss is to simply eat less and exercise more. The belief was that these two things were the biggest factors that affected your body weight. However, research now shows that this is not true.

In fact, research published in the Annals of Internal Medicine shows that getting less than seven hours of sleep per night can reduce or even undo any benefits of dieting. In that study, research subjects that slept over seven hours lost more weight, and over half of the weight lost was fat.

In contrast, when sleep was reduced to under seven hours, there was a 55% reduction in fat loss. Plus, those participants with less sleep felt hungrier, and less satisfied after meals. They also reported having less energy, which negatively impacted their exercise.

Not only, does a lack of sleep make it harder to lose weight, poor sleep is now believed to be one of the strongest risk factors for weight gain. This means that if you do manage to lose the weight while being sleep-deprived, the likelihood of you gaining it back is much higher than if you were well-rested.

Why are sleep and weight loss so strongly linked? Let’s look at some of the findings:

1. Sleep impacts your body’s hormone production

A lack of sufficient sleep has been shown to impact your metabolism and the hormones that control your fat cells, hunger signs, and cravings.

Insulin

Research shows that less than 7 hours of sleep per night negatively impacts your body’s ability to process insulin.

University of Chicago researchers found that four nights of too-little sleep resulted in insulin sensitivity dropping by more than 30 percent. As insulin sensitivity decreases, your body’s insulin levels increase and it triggers increased fat storage. Plus, it can lead to fat being stored in dangerous places, such as your liver, which is what can lead to you developing dangerous diseases such as type 2 diabetes.

Excess insulin in your bloodstream also makes you feel hungrier, which can make it more difficult to cut calories and lose weight.

Leptin & Ghrelin

Unfortunately, an increase in insulin is not the only reason a lack of sleep can make you feel hungrier. The two primary hormones that control your feelings of hunger are leptin and ghrelin.

Leptin is produced in your fat cells, and the less you produce, the hungrier you feel. Ghrelin works the opposite way; the more you produce, the hungrier you feel. The more ghrelin you produce, the slower your metabolism is as well, which means you burn less fat and store more.

To successfully lose weight, you want to increase your leptin output and decrease your ghrelin output. However, research published in the Journal of Clinical Endocrinology and Metabolism has shown that when you sleep less than six hours per night, the opposite happens: leptin decreases and ghrelin increases.

Cortisol

In addition, it’s been proven that a lack of sleep causes your cortisol levels to increase, and cortisol is a stress hormone that has been linked to fat gain. Cortisol is believed to activate reward centres in your brain that cause food cravings.

The combination of too much cortisol and ghrelin makes it much more difficult to feel satisfied after you’ve eaten, and increases the sensation of being hungry all the time.

2. Sleep affects your brain function

Even one night of sleep deprivation has been linked to the impairment of your frontal lobe, which is the area of your brain which controls complex decision-making. This results in you no longer having the mental clarity to make good decisions, especially when it comes to food and weight loss.

In addition, not enough sleep leads to increased activity in your brain’s amygdala, which is the reward centre of your brain. To make matters even worse, your insular cortex, which can help control impulses, is weakened when you don’t get enough sleep.

This is why weight loss techniques can easily be sabotaged by a lack of sleep. Basically, your cravings for calorie-rich foods are much more intense and your ability to ignore those cravings and make healthy decisions is significantly impaired.

Studies have shown that sleep deprivation not only increases your cravings, it also leads to you eating larger portions of food. In one study, when participants only experienced four hours of sleep per night, their calorie intake rose by 22% and their fat intake almost doubled!

3. Sleep affects your mood

Lack of sleep affects your mood in a big way. In fact, a study by the Sleep Research Institute shows that a reduction in sleep affects mood even more than energy levels or cognitive ability. People who are partially sleep deprived report more negative moods.

If you’re the type of person who finds comfort in food (and most people do!) then you may be more likely to overeat when you’re combating irritation and depression. Negative moods can be worsened when you don’t get a full night’s sleep. To make your experience with the hCG diet most effective, we recommend a healthy sleep schedule in addition to our diet plan.

Sleep and weight loss

While too little sleep has been proven to negatively affect weight loss, too much sleep isn’t healthy either. To achieve the greatest benefits, aim to sleep between seven and nine hours every night.