When Mental Health Changes Your Weight

Specialist CBT therapy for anxiety, OCD, depression and more in West London

Weight change is usually the last thing people mention and the first thing they apologise for. It is rarely an isolated physical event. Chronic stress, anxiety, and depression each alter the hormones that regulate appetite and the motivation to move — and those changes show up on the scale in ways that have nothing to do with willpower or discipline. Chronic stress keeps cortisol elevated, which disrupts the HPA axis and drives cravings for calorie-dense food. This is a physiological response, not a character failing. The same anxiety that causes weight gain in one person can suppress appetite entirely in another, depending on whether the stress is acute or chronic. Depression shows a genuinely bidirectional relationship with weight: each can drive the other. Low mood makes movement harder, and less movement feeds low mood right back. A 2025 systematic review found this bidirectional link between depressive symptoms and both physical activity and sedentary behaviour. The gut-brain axis — the bidirectional communication pathway linking gut microbiota to the brain's emotional centres — adds another layer: disruption in gut bacterial diversity has been linked to both depression and anxiety. Mediterranean-style dietary patterns show the most consistent evidence for mood benefit. For people taking antidepressants, weight change can be a treatment effect: mirtazapine, paroxetine, and amitriptyline are more consistently associated with weight gain, while bupropion is associated with weight loss or neutrality. CBT does not treat weight. It treats the anxiety, depression, or chronic stress driving appetite and activity in one direction or another. Addressing weight without addressing what is underneath it is like repainting a wall with a damp problem. BABCP-accredited CBT is available at The Lyceum Clinic in Chiswick, Hammersmith, and Ealing, West London, and online across the UK.