Same diet, different bodies
Why what works for one of you does nothing for the other.
The two of youYou eat the same meals and train together, but your bodies respond completely differently.
If carbs hit you harder, variants like those near FTO and TCF7L2 can mean stronger hunger signals and a sharper blood-sugar response, so the same rice affects you more than it affects your partner.
If your partner stays steady on the same plate, they may simply carry calmer versions of those variants, plus a different muscle and metabolism mix that responds differently to the same workout.
Stop comparing plates and results. Build meals around each person's response, more protein and fibre for the one who spikes, and judge progress against your own body, not your partner's.
Two partners can eat identically and train together yet see very different results, because how you handle carbs, build muscle, and respond to exercise is partly genetic and personal to each of you.
This is the one that quietly causes the most frustration, because it feels unfair. One partner changes nothing and stays lean, the other works hard for every result. It is not effort, it is wiring, the same food and the same workout meet two different bodies. The kindest move is to stop using each other as the benchmark and let each body be judged on its own terms.