In healthy, lean individuals, insulin reduces the breakdown of fat in both fat tissue and muscle, and muscle tissue requires less insulin to achieve this effect than fat tissue.

We analyzed the available evidence and found that in healthy, lean individuals, insulin reduces the breakdown of fat in both fat tissue and muscle tissue. The evidence we’ve reviewed suggests that muscle tissue needs less insulin than fat tissue to achieve this same effect [1]. This means that even at lower insulin levels, muscle stops breaking down fat more quickly than fat tissue does. We don’t know exactly why this difference exists from the data we’ve seen, but it points to a pattern where muscle is more sensitive to insulin’s fat-blocking action. What we’ve found so far is limited to one assertion with 41.0 supporting points and no refuting evidence, so we can’t say how this plays out in other populations, like those with excess weight or insulin resistance. We also don’t have data on how long this effect lasts or whether it changes with exercise or diet. For now, the pattern we see is that insulin acts as a brake on fat breakdown in both places, but muscle responds more strongly to smaller amounts of insulin. In everyday terms, this could mean that after eating, your muscles stop tapping into their fat stores sooner than your body fat does — which might help explain why fat tends to stick around longer after meals.