When you exercise or skip meals, your body makes a special protein called FGF-21 that helps it adapt and get healthier in response to the stress of those activities.

If you keep fasting or cutting calories for a long time without giving your body a break, your body might stop responding to a helpful hormone called FGF-21, and you won’t get as many health benefits from it anymore.

Your body's FGF-21 hormone works best in short bursts, but too much exercise in people with poor metabolism might make the body stop responding to it quickly.

If your metabolism isn't working well, short bursts of intense exercise with rest in between might help your body respond better and stay sensitive to the benefits over time.

If someone already has poor metabolic health, long-term stress might make their body stop responding to a helpful hormone called FGF-21, which means their cells can't handle stress well and things just keep getting worse.

Your body makes a hormone called FGF-21 when under stress, and it helps control how sensitive you are to insulin and how much belly fat you store — but how and how long it’s turned on really matters.