Is stress making you fat?
Short answer: yes, through more than one mechanism. As ever, nuance matters.
What’s the evidence that stress and obesity are even related?
In a Norwegian study of >23,000 adults, the authors showed a significant relationship between obesity and psychosocial stress (defined as experiencing relationship problems, sudden family death, bullying, divorce, violence, etc). In the study 24% of people reported none of these stressors while 60% reported 1-3 stressors and 15% reported 4-7 stressors.
The study authors: “For every one-unit of increase in number of psychosocial stressors, the odds of falling into a higher category of BMI increased”, meaning that every time you experience a traumatic life event the likelihood of becoming obese increases.
But how?
There is a lot here and I will only talk about cortisol, which is released when we are exposed to stress. Cortisol promotes obesity through several mechanisms, I will only cover two:
Cortisol makes you eat: This has been shown in studies where people take a synthetic glucocorticoid (mimics cortisol) and asked to keep a food diary. One could challenge this study by saying that the synthetic compound may act differently to our natural cortisol. This would be a completely fair challenge, but another study repeated the same experiment with a stressor in the lab (instead of taking a pill). Guess what, those exposed to stress, ate more than those who were not stressed out.
Cortisol makes you store fat: Particularly around the abdomen, and this is a hallmark symptom in Cushing’s disease; a hormonal imbalance where the adrenal gland secretes excessive amounts of cortisol (amongst other symptoms). Treating the condition and medically reducing blood cortisol reverses the abdominal obesity in some patients. In fact, if you look at the side effects of hydrocortisone tablets (steroids that mimic the effect of cortisol), you will see “Cushingoid state” and “weight gain”.
Am I really getting fat because I’m stressed out?
After all that’s been said, I can tell you that it’s really not that simple. The key ingredient that I haven’t addressed is time. Being stressed out for a week or so for a deadline at work is not going to make any material difference. The risk of weight gain really comes with chronic stress exposure. I think of stress the same way I think about diet; if I over eat for a day a week, I don’t have a problem. But if I over eat 6 days a week for most of the year, I’m sure I will balloon. Stress works in the same way, the more you experience it, the more it impacts you.
This is good news, because every single day, you have the opportunity to choose to mitigate stress and reduce the chance of weight gain.
Sources
Eik-Nes TT, Tokatlian A, Raman J, Spirou D, Kvaløy K. Depression, anxiety, and psychosocial stressors across BMI classes: A Norwegian population study - The HUNT Study. Front Endocrinol (Lausanne). 2022 Aug 10;13:886148. doi: 10.3389/fendo.2022.886148. PMID: 36034441; PMCID: PMC9399822.
Tomiyama AJ. Stress and Obesity. Annu Rev Psychol. 2019 Jan 4;70:703-718. doi: 10.1146/annurev-psych-010418-102936. Epub 2018 Jun 21. PMID: 29927688.
Hydrocortisone 10 mg Soluble Tablets. Summary of product Characteristics. Last updated Nov 2022. Available at https://www.medicines.org.uk/emc/product/13254/smpc. Accessed Mar 2025.