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Eating late increases hunger, decreases calories burned, and changes fat tissue

Obesity afflicts approximately 42 percent of the U.S. adult population and contributes to the onset of chronic diseases, including diabetes, cancer, and other conditions. While popular healthy diet mantras advise against midnight snacking, few studies have comprehensively investigated the simultaneous effects of late eating on the three main players in body weight regulation and thus obesity risk: regulation of calorie intake, the number of calories you burn, and molecular changes in fat tissue.

A new study found that when we eat significantly impacts our energy expenditure, appetite, and molecular pathways in adipose tissue. Their results are published in Cell Metabolism.

"We wanted to test the mechanisms that may explain why late eating increases obesity risk," explained senior author Frank A. J. L. Scheer, PhD, Director of the Medical Chronobiology Program in the Brigham's Division of Sleep and Circadian Disorders. "Previous research by us and others had shown that late eating is associated with increased obesity risk, increased body fat, and impaired weight loss success. We wanted to understand why."

"In this study, we asked, 'Does the time that we eat matter when everything else is kept consistent?'" said first author Nina Vujovic, PhD, a researcher in the Medical Chronobiology Program in the Brigham's Division of Sleep and Circadian Disorders. "And we found that eating four hours later makes a significant difference for our hunger levels, the way we burn calories after we eat, and the way we store fat."

Vujovic, Scheer and their team studied 16 patients with a body mass index (BMI) in the overweight or obese range. Each participant completed two laboratory protocols: one with a strictly scheduled early meal schedule, and the other with the exact same meals, each scheduled about four hours later in the day. In the last two to three weeks before starting each of the in-laboratory protocols, participants maintained fixed sleep and wake schedules, and in the final three days before entering the laboratory, they strictly followed identical diets and meal schedules at home. In the lab, participants regularly documented their hunger and appetite, provided frequent small blood samples throughout the day, and had their body temperature and energy expenditure measured. To measure how eating time affected molecular pathways involved in adipogenesis, or how the body stores fat, investigators collected biopsies of adipose tissue from a subset of participants during laboratory testing in both the early and late eating protocols, to enable comparison of gene expression patterns/levels between these two eating conditions.

Results revealed that eating later had profound effects on hunger and appetite-regulating hormones leptin and ghrelin, which influence our drive to eat. Specifically, levels of the hormone leptin, which signals satiety, were decreased across the 24 hours in the late eating condition compared to the early eating conditions. When participants ate later, they also burned calories at a slower rate and exhibited adipose tissue gene expression towards increased adipogenesis and decreased lipolysis, which promote fat growth. Notably, these findings convey converging physiological and molecular mechanisms underlying the correlation between late eating and increased obesity risk.

These findings are not only consistent with a large body of research suggesting that eating later may increase one's likelihood of developing obesity, but they shed new light on how this might occur. By using a randomized crossover study, and tightly controlling for behavioral and environmental factors such as physical activity, posture, sleep, and light exposure, investigators were able to detect changes the different control systems involved in energy balance, a marker of how our bodies use the food we consume.

This study shows the impact of late versus early eating. They isolated these effects by controlling for confounding variables like caloric intake, physical activity, sleep, and light exposure, but in real life, many of these factors may themselves be influenced by meal timing.

10 Ways to Stop Eating Late at Night

Many people find themselves eating late at night, even when they are not hungry. Nighttime eating can cause you to eat more calories than you need, which can lead to weight gain.

1. Identify the cause

Some people eat most of their food late in the evening or during the night. To change this habit, you need to identify the cause of the problem. Nighttime eating may be the result of overly restricted daytime food intake, leading to hunger at night. Habit or boredom may also be the cause. However, nighttime eating has also been linked to some eating disorders, including binge eating disorder and night eating syndrome.

These two disorders are characterized by different eating patterns and behaviors, but they can have the same negative effects on your health. In both, people use food to curb emotions such as sadness, anger or frustration, and they often eat even when they are not hungry. Binge eaters also tend to eat very large amounts of food in one sitting and feel out of control while they are eating. On the other hand, people with nighttime eating syndrome tend to graze throughout the evening and wake up during the night to eat, consuming at least 25% of their daily calories at night.

Both conditions have been linked to obesity, depression, and trouble sleeping.

2. Identify your triggers

As well as identifying the overall cause of your overeating, you may find it useful to look for a specific pattern of events that usually sets off your eating behavior. People reach for food for many reasons. If you’re not hungry but nonetheless find yourself eating at night, think about what led up to it. Often you will find you are using food to meet a need that is not hunger. With nighttime eating syndrome, your entire eating pattern may be delayed due to your lack of daytime hunger.

One effective way to identify the cause of your nighttime eating and the things that trigger it is to keep a “food and mood” diary. Tracking your eating and exercise habits alongside your feelings can help you identify patterns, enabling you to work on breaking any negative cycles of behavior.

3. Use a routine

If you’re overeating because you aren’t eating enough during the day, getting yourself into a routine may be helpful. Structured eating and sleeping times can help you spread your food intake over the day so that you’re less hungry at night. Getting good quality sleep is vital when it comes to managing your food intake and weight.

According to a 2015 review of studies, lack of sleep and short sleep duration have been linked to higher calorie intake and poor-quality diets. Over a long period of time, poor sleep can increase your risk for developing obesity and related chronic diseases. However, as the review noted, though sleep plays an important part in eating patterns, other factors are involved such as appetite-related hormones and time frames around food intake.

Having set times for eating and sleeping can help you separate the two activities, especially if you are prone to waking in the night to eat.

4. Plan your meals

As part of your routine, you may also benefit from using a meal plan. Planning your meals and eating healthy snacks can help reduce the chances that you will eat on impulse and make poor food choices.

A 2013 study looked at the relationship between food and impulsivity. Study participants were people with overweight or obesity who either had BED or didn’t have the condition. Results showed that the mere sight of food can act as a trigger for the body’s reward and disinhibition responses. Researchers observed this happened more often in participants who had BED.

Having a meal plan can also reduce any anxiety about how much you are eating and help you spread your food throughout the day, keeping hunger at bay.

5. Seek emotional support

If you think you may have nighttime eating syndrome or binge eating disorder, you may want to speak with a doctor. If needed, they can refer you to a mental health professional who can help you identify your triggers and implement a treatment plan. These plans often use cognitive behavioral therapy (CBT), which has been shown to help with many eating disorders.

In a 2015 randomized controlled study, researchers compared the rapid-response and long-term impact of using three different therapeutic treatment methods, including CBT, in treating 205 people with confirmed BED diagnoses. Results showed the best outcomes, both short term (rapid response) and long term (remission), resulted from the use of CBT.

Creating an emotional support network will also help you find ways to manage negative emotions, which otherwise might lead you to the fridge.

6. De-Stress

Anxiety and stress are two of the most common reasons why people eat when they are not hungry. However, using food to curb your emotions generally tends to be a temporary solution. If you notice that you eat when you are anxious or stressed, try to find another way to let go of negative emotions and relax. Research has shown that relaxation techniques can help manage eating disorders such as nighttime eating syndrome and binge eating.

In a 2003 study, 20 people with a confirmed diagnosis of night eating syndrome (NES) were randomly assigned to one of two groups for an equal amount of time over a period of 2 weeks.

One group received Abbreviated Progressive Muscle Relaxation Therapy (APRT), while the second group was placed in a controlled relaxation environment that provided similar benefits. Results showed that with just 20 minutes of APRT, participants benefited from lower stress levels. Over the 8-day period of practicing this technique daily, participants showed higher morning and lower nighttime hunger rates.

Relaxation techniques you may find useful include:

  • breathing exercises

  • meditation

  • hot baths

  • yoga

  • gentle exercise

  • stretching

7. Eat regularly throughout the day

Overeating at night has been linked to erratic eating patterns that can often be categorized as disordered eating. Eating at planned intervals throughout the day in line with “normal” eating patterns can help keep your blood sugar stable. It can also help prevent you from feeling famished, tired, irritable or having a perceived lack of food, which may lead to a binge.

When you get really hungry, you are more likely to make poor food choices and reach for high fat, high sugar and processed foods. Studies find that those with regular meal times (eating 3 or more times per day), have better appetite control and lower weight. Generally speaking, eating less than 3 times per day is thought to reduce your ability to manage your appetite and food choices.

The best eating frequency for managing hunger and the amount of food consumed is likely to vary among people.

8. Include protein at every meal

Different foods can have different effects on your appetite. If you eat due to hunger, including protein at every meal may help curb your hunger. It could also help you feel more satisfied throughout the day, stop you from being preoccupied with food and help prevent snacking at night..

A 2011 study looked at consuming high-protein (HP) vs. normal-protein (NP) meals and the frequency of consuming them to determine if the effect of this combination method on managing hunger. The study involved 47 men who were overweight or had obesity. Results found that eating high-protein meals reduced cravings by 60% and cut the desire to eat at night by half, but frequency did not significantly impact outcomes overall.

9. Stock up on healthy snacks that are readily accessible

If you are prone to eating high fat, high sugar and highly processed foods, try to limit your consumption. If snacks with low nutritional value are not within easy reach, you are much less likely to eat them.

Instead, fill your house with nutrient-rich food that you enjoy. Then when you have the urge to eat, you won’t snack on junk. Good snack-friendly foods to have available if you get hungry include fruits, nuts, berries, plain yogurt and cottage cheese.

10. Distract yourself

If you are preoccupied with thoughts of food because you’re bored, then find something else you enjoy doing in the evening. Try going for a walk, calling a friend, reading or researching recipes for healthy recipes. Finding a new hobby or planning evening activities can help prevent mindless late-night snacking.



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