When we are under a lot of stress, we are not only more likely to overeat but we are also more likely to eat foods that are high in sugar and fat. Researchers at the University of California, San Francisco, have discovered a link between chronic stress and obesity; people who have high-stress levels produce higher levels of the hormone called cortisol, which often leads to increased eating of high-caloric foods, including sugar and candy.
To complicate matters, high levels of cortisol circulating in the blood result in an increase in the mobilization of protein breakdown from muscle tissue, a process known as gluconeogenesis. This protein is converted to glucose for energy. Also, if the increased blood sugar is not used immediately for energy use, it is stored as abdominal fat. This is why chronic sustained stress leads to muscle loss as well as fat deposition. Loss of muscle mass is a serious problem as muscle is metabolically very active and helps to increase metabolism, which is essential for weight loss.
Furthermore, as cortisol is increased, it continues to raise the blood sugar level and lead to the increase of its opposing hormone, insulin. Insulin lowers glucose when it is too high. If insulin production remains higher than normal for sustained periods, this can lead to a pre-diabetic condition known as metabolic syndrome.
New Scientist  reported a study by Kent Berridge of the University of Michigan, Ann Arbor, which showed that stress may trigger binge eating by changing how we value a reward. They showed that stress may increase our desire for pleasurable experiences while not actually increasing our sense of enjoyment. In a series of rat experiments, they demonstrated that stress magnified the desire for sugar, particularly when accompanied by a cue or tone that advertised the reward of the sugar treat: “It is a bit like seeing an advert for ice cream which makes you desire it,” he says. “If you are not stressed, you can resist, but together, the stress and the advert make it irresistible.”
Berridge’s team injected a corticotropin-releasing factor stress hormone into the nucleus accumbens of rats’ brains, which is part of the dopamine reward circuitry responsible for desire. These rats had been trained to press a lever to receive a dose of sugar and to associate hearing a certain tone with getting the sugar. The stressed rats worked harder at pressing the lever when they heard the tone than rats with low-stress hormones did.
When amphetamines, which are known to increase desire, were injected into the rats, the effect was exactly the same. These findings may explain why some stressful pursuits can be rewarding and also how the presence of drug paraphernalia and stress make drug relapse almost inevitable.
Cortisol also interferes with a protein known as tyrosine, which is essential for thyroid hormone production. Excess cortisol leads to decreased thyroid function and a lowered metabolic rate, a further problem in weight gain. On an average day, most people experience eight to ten major triggers to their stress response. It has been estimated that our autonomic nervous systems are designed to respond to a major stressor only every three months. Each time our stress response is activated and our cortisol levels go up, we sometimes experience an urge to eat something soothing or stimulating. Our stress responses, also known as fight-or-flight responses, can be triggered by many everyday occurrences, such as being involved in an upsetting conversation or interaction, being cut off in traffic, realizing that we have left an important document at home, or not being able to find our keys.
Not only can stress make unhealthy foods more tempting, but it can also impair our bodies’ processes of digesting our food and absorbing nutrients. The best time to eat is when you are feeling safe and relaxed because that is when your body can digest food most efficiently and thereby enhance your metabolism, which leads to fat loss.
Action Plan for Stress-Free Eating: Dos and Don’ts
- Eat while sitting down in a relaxed atmosphere.
- Eat at a comfortable pace; stay conscious of the process.
- Chew every bite many times before swallowing.
- Set your fork or spoon down on your plate between bites.
- Take a moment to feel grateful for the food and the person or people who prepared it for you.
- Pay attention to the internal signals that tell you when you are full
- Eat in silence for one meal each week, savouring the flavour of each mouthful of food
- Remember that food is for nutrition. Continuing to eat after you are satisfied overloads the digestive system, resulting in a build-up of toxicity in your body
- Learn to include a variety of the six tastes in your meals: sweet, sour, salty, bitter, pungent, and astringent. Each taste has a subtle yet distinct effect on our physiology.
- Kindle your appetite by eating a few pieces of freshly sliced ginger sprinkled with lemon juice fifteen minutes before your meal.
- Eat freshly prepared foods. Lightly cooked foods are preferable to raw or over-cooked foods.
- Sit quietly for a few minutes after finishing your meal. Focus your attention on your bodily sensations.
- Don’t watch TV, drive, or have upsetting conversations while eating.
- Don’t eat out of boxes or bags. Put your food on a plate or in a bowl.
- Don’t eat while highly emotional.
- Don’t eat while driving
- Don’t eat unless you feel hungry. Think of your capacity for food as an “appetite gauge,” whereby 1 on the dial means that you are famished and 10 means that you are completely full. Eat when your appetite drops to around 2 or 3.
- Don’t eat any more when you’re satisfied or when your “appetite gauge” is 6 or 7.
- Don’t eat or drink too many ice-cold foods and beverages, as these can significantly reduce the absorption of specific foods by diluting the acid produced by your stomach, which is essential for protein breakdown.
- Don’t eat erratically when your life is hectic and you are suffering from high levels of stress. This will lead to inefficient energy production, weight gain, and obesity.
Use Your Breath to Lower Your Stress
- Before you begin your meal, sit quietly and close your eyes. Then do the following:
- Breathe in slowly to the count of four.
- Hold your breath to the count of four.
- Breathe out to the count of four.
- Hold the exhale to the count of four.
- Repeat the cycle three times
This exercise will reset your autonomic nervous system, shifting it from a fight-flight-activated stress response (which shuts down digestion and gut motility) to a rest, relaxed, and digestive healing response (which optimizes motility and the absorption of nutrients), lowering the stress hormone cortisol in the process.
*1. Berridge K, New Scientist April 2016
*2. BMC Biology, DOI: 10.1186/1741-7007-4-8