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4 min readExpert-reviewedUpdated 4 Jun 2026

Why the same diet transforms your friend and does nothing for you

Same plate, two bodies, two completely different stories.

Short answer

The same diet works differently because variants in genes like FTO, TCF7L2 and MC4R shape your appetite, how you store fat and how your body handles carbs, so two people eating identically can see very different fat loss and hunger results.

Key takeaways
  • FTO and MC4R shape appetite and fullness, so the same meal leaves some people hungrier.
  • TCF7L2 affects how your body handles carbs and insulin, changing fat storage.
  • South Asians are often more insulin-resistant at lower body weights.
  • Genes set difficulty, not destiny; your own response matters more than a friend's plan.

Your friend cuts rice and drops weight in a month. You do the same and barely move. Genetics is one big reason. The FTO gene influences appetite and how full you feel after eating, so some people stay hungrier on the same meal. MC4R works alongside it in the brain's hunger circuit. TCF7L2 affects how your body manages blood sugar and insulin, which changes how carbohydrate-heavy meals like dal-chawal land for you versus someone else.

These variants are common, not rare. Roughly one in two people of South Asian descent carries at least one higher-risk FTO variant, and South Asians tend to be more insulin-resistant at a given weight than many European populations. That means a high-carb Indian diet can push blood sugar and fat storage harder in some of us, even at a lower body weight. None of this is a single broken gene; it is many small nudges adding up.

The honest takeaway: your genes set the difficulty level, not the outcome. If carbs hit you hard, a protein-forward plate, more fibre, walking after meals and steady sleep usually help more than copying a friend's plan. Genetics explains why one-size-fits-all diets disappoint, and why your own response is the data that matters most.

People also ask

Does the FTO gene mean I cannot lose weight?

No. FTO nudges appetite upward but people with risk variants still lose weight with diet and activity; it just may take more attention to hunger and protein.

Are these genes common in Indians?

Yes, FTO and TCF7L2 risk variants are common across South Asian populations, which partly explains higher diabetes and weight-related risk at lower body weights.

Should I get a DNA test before dieting?

Not necessary to start. Tracking your own response to meals is more useful day to day; a test mainly adds context, not a prescription.

Sources
  • Frayling TM et al., Science 2007 — FTO and body weight
  • Loos RJF, Yeo GSH, Nature Reviews Endocrinology 2014 — FTO biology
  • ICMR-INDIAB studies — insulin resistance and metabolic risk in Indians

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