Even if you don’t eat much, several factors can contribute to weight gain, including:

Genetics – Variants in genes like FTO can slow metabolism, increase fat storage, and affect how full you feel.

Hormonal imbalances – Conditions like hypothyroidism or insulin resistance can reduce energy expenditure.

Low muscle mass – Less muscle means a slower resting metabolism.

Sedentary lifestyle – Even with low calorie intake, limited movement can lead to weight gain.

Underestimating calories – Portion sizes, hidden sugars, and processed foods can add up without seeming like much.

Stress & sleep – Chronic stress and poor sleep increase cortisol and hunger hormones, which can trigger fat storage.

If you suspect a genetic factor, a DNA test for obesity can help reveal whether your body has a predisposition to weight gain—empowering you to tailor your lifestyle for better results.