Stress and weight gain

During stress, we adapt our physiology and behaviour so that we are able to survive. This is known as the stress response. Under normal conditions, the stress response is vital and healthy. However, when activated repeatedly, it can have negative effects on our health. An over activated stress response is associated with weight gain and many chronic diseases. This article highlights ways in which stress can influence weight gain.

The stress response

A stress is a perceived threat, which can be mental, physical, or emotional. In response to a perceived threat, various physiological processes are activated, stress hormones known as cortisol and adrenaline are released and the cardiovascular, nervous, endocrine and immune systems are all influenced as a result. Overall, the stress response results in physiological and behavioural adaptations to increase the chances of survival.

Physical adaptations

Increased breathing rate, increased blood pressure and heart rate, energy is redirected to vital functions, blood sugar (glucose) levels increase, fat stores mobilised and blood flow is redirected to vital areas. At the same time, energy consuming functions are suppressed, such as digestion, reproduction and growth and there may be alterations to the immune response.

Behavioural changes

Increased alertness, arousal and vigilance, focused attention, suppression of feeding behaviours.

Each individual’s stress response will vary due to his or her genes, lifestyle factors and health status and it should be noted that acute stress and chronic stress often result in very different behavioural changes.

Blood sugar (glucose) levels

Because the body is trying to generate energy to move away from the stress, the stress hormones activate the release of glucose into the bloodstream predominantly from the liver. Depending on what you are doing at the time of the stress or the type of the stress (physical vs emotional), the increased glucose is delivered to the brain and muscles to aid the stress response. The challenges come when one is sedentary undergoing these types of stress as this may then result in elevated glucose, elevated insulin and thus a higher risk of fat being formed from the available glucose and fatty acids.

For some people, elevated glucose can subsequently result in a reactive reduction in blood glucose. This response can then trigger a desire for food once again, typically higher sugar foods. (1).

Fat stores

Cortisol affects fat metabolism: it breaks down fat and then transports it to the abdomen to be stored as visceral fat, the fat that is stored around the organs. It then helps the fat stores to grow and develop (2). Excess cortisol results in a two to five fold increase in central visceral fat stores (2) and visceral weight gain is strongly associated with insulin resistance, cardiovascular disease and type 2 diabetes (3).

Cortisol also functions to inhibit the effects of the hormone insulin, whilst enhancing the action of the hormone glucagon. This further contributes to hyperglycaemia and insulin resistance (4). Insulin resistance then further exacerbates weight gain and makes it harder to lose weight, since higher levels of insulin are present and insulin promotes fat-storage! Check out Insulin resistance and weight gain: chicken or egg? to learn more.

Appetite levels

Appetite can be increased or decreased in response to stress. Stress hormones can impact appetite directly and interact with appetite hormones. Whether appetite is increased or decreased depends on different factors such as the severity of stress, the variation in the individual response and which stress pathways are activated (5). For example, stress induced eating in overweight women is characterised by a stronger motivation to eat and absence of fullness signals (6). Stress also affects how slowly or quickly food leaves your stomach, as well as bowel movement, which may influence appetite levels.

Dietary choices

Stress may affect the type of food chosen. During periods of stress, individuals are more likely to choose sweet and fatty foods (7,8). Emotional eaters are at greater risk of overeating (8) and a greater perceived stress is associated with higher overall energy intake (9). People who are stressed, indicated by levels of cortisol, are more likely to snack throughout the day (10), which may result in a higher energy intake. A diet high in sugar, fat and excess energy will result in weight gain, as well as being associated with insulin resistance which will further exacerbate the weight gain.

Physical activity

Stress results in behavioural adaptations to manage the stress. This behavioural response will differ depending on the person. Becoming more or less physically active during periods of stress will depend on the individual (11). For some people, exercise is a go to during times of stress whereas for other it is not. Obviously if stress results in a decrease in activity, then this will be a contributing factor to weight gain.

Sleep

Periods of high emotional stress are predictive in reduced sleep time (12) increases in stress and worries at bedtime are associated with impaired sleep (13) and work stressors have a direct relationship to sleep disorders (14).

Insufficient sleep is associated with higher total energy intake, higher total fat intake and lower quality diets (15). Sleep-restricted individuals prefer fat and carbohydrate rich foods (16) and increase their daily caloric intake by approximately 20% (17). Also, short sleep duration actually decreases the amount of fat that overweight subjects lose during caloric restriction (18).

Short sleep times are associated with increased risk of significant weight gain and obesity (19). Sleep disturbance is associated with inflammation (20) and sleep restriction is associated with insulin resistance (21), both of which are associated with weight gain. Both sleep quantity and quality influence the ratio of appetite regulating hormones (leptin and ghrelin), which may result in an increased drive to eat (22).

Take away messages

Identify your stressors

What are your key stressors? Maybe the work ones are obvious but what about emotional? Take out a notepad and spend 5 minutes jotting down your key stressors. If you’re not sure, maybe ask a loved one/friend – although be prepared to be stressed!

Get to know your stress response

Stress and the stress response are incredibly complex and there are vast differences in the way that people respond. Your own response may also change depending on the type of stressor. How do you most instinctively respond to stress? Angry, anxious, irritated? Become aware. Becoming aware is the first step to being able to manage it.

Create a stress mitigation plan and implement it

Research shows that having a plan to prepare for stress and therefore mitigate it is far more effective than reducing stress at the time. Additionally, build in regular opportunities to do what you love to build reserves against stress and practice techniques you can utilise if you do need to de-stress. Check out Learn how to manage stress and chill out like a pro for tips!

If you enjoyed this article, you may also enjoy the following related articles:

• Learn how to manage stress and chill out like a pro
• Insulin resistance and weight gain: chicken or egg?

References

1. Bumbu et al. (2017). Non-severe hypoglycaemia is associated with weight gain patients with type 1 diabetes: results from the diabetes control and complication trial.
2. Lee et al. (2014). Deconstructing the roles of glucocorticoids in adipose tissue biology and the development of central obesity.
3. Eckel et al. (2011). Obesity and type 2 diabetes: what can be unified and what needs to be individualised?
4. Kuo et al. (2015).Regulation of glucose homeostasis by glucocorticoids.
5. Torres et al. (2007). Relationship between stress, eating behaviour, and obesity.
6. Glasker et al. (2018) Stress, endocrine physiology and pathophysiology
7. Epel et al. (2001). Stress may add bite to appetite in women: a laboratory stress-induced cortisol and eating behaviour.
8. Oliver et al. (2000). Stress and food choice: a laboratory study
9. McCann et al. (1990). Changes in plasma lipids and dietary intake accompanying shifts in perceived workload and stress.
10. Roberts et al. (2013). Increases in weight during chronic stress are partially associated with a switch in food choice towards increased carbohydrate and saturated fat intake
11. Burg et al. (2017). Does stress result in you exercising less? Or does exercising result in you being less stressed? Or is it both?
12. Sadeh et al (2004). Effects of stress on sleep: the moderating role of copying style
13. Akerstedt et al. (2007). Impaired sleep after bedtime stress and worries.
14. Kalimo et al. (2000). Job stress and sleep disorders: findings from the Helsinki Heart Study.
15. Dashti et al. (2015). Short sleep duration and dietary intake: epidemiological evidence, mechanisms and health implications.
16. St Onge et al. (2011). Short sleep duration increases energy intakes but does not change energy expenditure in normal-weight individuals.
17. Nedeltcheva et al. (2009). Sleep curtailment is accompanied by increased intake of calories from stress
18. Nedeltcheva et al. (2010). Insufficient sleep undermines dietary efforts to reduce adiposity.
19. Ning et al. (2020). Association of sleep duration with weight gain and general and central obesity risk in Chinese adults: a prospective study.
20. Irwin et al. (2016). Sleep disturbance, sleep duration and inflammation: a systematic review and meta-analysis of cohort studies and experimental sleep deprivation
21. Buxton et al. (2010). Sleep restriction for 1 week reduces insulin sensitivity in healthy men.
22. Spiegel et al. (2004). Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite.