In the ideal world, losing body fat would be as simple as eating less and moving more. But study after study shows that fat loss is more complicated, especially over the long term. Research points to chronic stress as having a significant impact on food intake and body fat with a clear association between higher levels of stress and obesity.
Understanding the link between stress and body fat is never more important. Just when obesity rates are surging in the western world, the coronavirus added a whole new level of anxiety to our daily lives. Many people responded by eating their way through the pandemic.
This research review will discuss how stress is linked with fat gain and show how stress management may be the magic bullet for improving body composition over the long term.
Stress Increases Food Intake
Stress is linked with a high risk of weight gain, especially the dangerous kind of fat that accumulates around the abdominal area. Anytime you are stressed, you experience activation of both the sympathetic fight-or-flight response and the hypothalamic-pituitary-adrenal axis that leads to the release of the stress hormone cortisol. Scientists theorize that activation of this neuroendocrine stress response stimulates eating for several reasons:
At the most basic level, eating makes us feel good. It leads to the release of opioids, dopamine, and endocannabinoids that stimulate reward areas in the brain. These are the same chemicals that are released in response to drugs—opioids in response to opiates like oxycodone and heroin, dopamine in response to cocaine, and endocannabinoids in response to marijuana. Besides making you feel pleasure, eating blunts the activation of the HPA axis, literally reducing sensations of stress.
A second factor is that eating—particularly high-carb foods—leads to the release of insulin, which is a hormone that acts as a cortisol antagonist. When blood sugar is elevated and insulin is released, cortisol begins to go down, easing your experience of stress. This is the reason many people crave high-carb foods—it’s a protective mechanism to help keep cortisol and stress in check.
This reality leads people to eat out of habit to make themselves feel better. Studies consistently show that people who “eat in the absence of hunger” have higher body fat and are more prone to obesity than those who don’t have this habit. Scientists theorize that high levels of cortisol “turn off” rational, goal-oriented parts of the brain. Even if you have every intention of eating a healthy meal of protein and vegetables, you’ll be overwhelmed with a desire for bread, cake, chips, or some other high-carb delight when your stressed.
Stress Hampers Sleep, Affecting Blood Sugar & Calorie Intake
A lot of times we can’t sleep because we’re stressed, but trouble sleeping is equally stressful. It’s a vicious cycle. Naturally, after a night of disrupted sleep, cortisol will increase, making us more likely to choose unhealthy, high-carb foods and nosh mindlessly. One study found that when subjects had their sleep disrupted, they increased food intake by 300 calories the following day, choosing high-fat, high-carb processed foods over healthier choices (1).
Conversely, another weight loss study that assessed sleep duration and quality found that for every 1 hour increase in sleep, subjects had a decrease of 0.7 kg of body fat (2). Another study found that among 245 women who were enrolled in a weight loss program, those who reported better sleep quality had a 33 percent increase in successful weight loss (3).
Stress Makes Us Lazy, Lowering Energy Expenditure
Because stress triggers a cascade of hormonal changes it has a negative impact on energy expenditure, both by lowering metabolic rate and by making us less physically active. Studies consistently show that people are more sedentary and exercise less when suffering from chronic stress.
Additionally, high cortisol alters the release of other hormones such as testosterone, estrogen, and thyroid hormone, all of which are involved in metabolic rate. The result is a drop in the amount of calories your body burns daily
Stress Management Improves Fat Loss
The good news is that two randomized trials show that strategies for coping with stress improve fat loss when combined with a diet and/or exercise intervention. One study of overweight middle-aged Greek women tested the effect of a stress reduction program in conjunction with a diet that cut 600 calories a day. The women were split into two groups: One that did stress management activities, such as deep breathing and mindfulness, and a control group that made no behavioral changes (4).
Results showed that the stress management group lost three times as much weight over 8 weeks, reducing body weight by 4.44 kg compared to only 1.38 kg loss in the control group. The stress management group also had significantly greater dietary restraint, which is a key skill for maintaining weight loss with dieting.
Dietary restraint differs from dieting: Restraint is defined as having conscious control of eating and is linked with lower body mass. Dieting, on the other hand, is rarely clearly defined and is associated with weight gain through triggering overeating.
A second study of African American women with high levels of obesity and stress were put on a lifestyle program to improve diet and physical activity (5). Half were also giving stress management tips. The stress management program included deep breathing, guided relaxation, cognitive strategies (positive thinking), and stress reducing activities like talking with friends or listening to music.
Results showed that over 3 months, the stress management program led to double the weight loss (-2.7 percent body fat) compared to the lifestyle program alone (-1.4 percent decrease). Cortisol also decreased significantly in the stress management group whereas there was no change in the diet-only group.
Scientists theorize that stress management calms the HPA axis that is linked with overeating. This may improve balance of hunger hormones, lowering ghrelin and neuropeptide Y that stimulate appetite, while improving the brain’s response to leptin that reduces food intake.
Nutrient Deficiencies, Stress & Fat Loss
An often overlooked piece of the stress-obesity puzzle is nutrient deficiencies. Deficiencies in vitamin D, niacin (B3), folate (B9), vitamin B6, vitamin B12, and omega-3 fatty acids have all been shown to increase susceptibility to stress and depression. For example, a study found significant associations between levels of B vitamins and psychological stress, in particular vitamin B12 (1).
How restoring nutrient levels would impact body fat is unclear but scientists theorize doing so may improve our ability to handle stress, reducing stress-related eating behaviors and overall energy intake.
Researchers point to the fact that the government recommended intake (RDA) for many nutrients is insufficient to account for brain requirements when under stress. These deficits compromise psychic and mental function through stress.
Several studies show supplementation with multivitamin or specific nutrients can improve the brain’s response to stress. A meta-analysis found that a combination of B vitamins, calcium, and magnesium has beneficial effects on stress, anxiety, and mood (1). Low intake of omega-3s from fish oil is also linked with depression and supplementation has been shown to help counter depression. Among healthy adults, 6 weeks of supplementation with fish oil showed a tendency to reduce cortisol concentration (6). Subjects also experienced a small decrease in body fat of about 2 pounds while increasing lean mass by about a pound.
Weight loss is often reduced to the “move more, eat less” paradigm. In reality, it’s much more complicated and a more holistic approach is recommended:
Stress management through deep breathing, mindfulness, and other proven activities for lowering cortisol should be included with nutrition and exercise for reducing body fat.
Ensuring adequate levels of nutrients that help the brain handle stress may improve mood and promote homeostasis despite the challenges of daily life. The B vitamins, magnesium, omega-3 fatty acids (fish oil), and vitamin D are especially important. Getting restful sleep is critical. Sleep plays an important role in recovery from stress and being well rested encourages people to make better eating choices.