How long should a bulk or cut actually last

Most people pick a phase, bulk or cut, and just stay in it until they're fed up or the mirror tells them to stop. That's not really a plan. Both phases have a natural shelf life, and running them too long works against you.

Why cuts shouldn't drag on

A deficit is a bit of stress on your body. The deeper or longer it runs, the more your body pushes back: hunger climbs, workouts feel flatter, and you start losing muscle along with fat if you lose weight too fast. Research on weight loss rates found that losing 1 kilogram a week instead of 0.5 kilogram led to a bigger drop in strength and testosterone in trained women over four weeks. A slower, steadier loss protects your lifts and your muscle.

• About half a percent to one percent of your bodyweight lost per week is a reasonable pace for most people.
• A cut lasting beyond around 8 to 12 weeks tends to get harder to stick to and harder on performance.
• The deeper the deficit, the shorter it should run.

Why bulks need a limit too

A surplus has the opposite problem. Keep pushing it for months and most of what you add stops being muscle and starts being fat. A study comparing a small surplus with a much larger one in people who already trained found that the larger surplus didn't build more muscle but did add more fat under the skin. There's a point past which more food just means more fat, not more gains.

A gentle surplus, gaining somewhere around a quarter to half a percent of your bodyweight a week, tends to give your muscles enough extra fuel without piling on fat you'll just have to cut later.

Taking a break in the middle

You don't have to grind a cut or bulk in one unbroken stretch. Some researchers have tested cycling short stretches of dieting with short stretches at maintenance, and found it can keep fat loss going while letting the body's energy use bounce back a little between cycles. One trial using 30-day cycles of dieting followed by a maintenance stretch reported steady weight loss with a rebound in resting energy use during the maintenance weeks. This is still early, small-study evidence, so think of it as one option, not a proven rule.

A deficit or a surplus both have a shelf life, and running past it works against you.

How to tell it's time to switch

1. 1

   Check your trend, not one weigh-in. Look at the smoothed direction of your bodyweight over two to three weeks rather than a single number.

2. 2

   Watch your lifts. If weights you used to move are stalling for several sessions in a row on a cut, that's a sign the deficit may be too deep or too long.

3. 3

   Notice how you feel in the gym. Constant low energy, poor sleep or dreading training are reasons to consider a break, not a reason to push harder.

4. 4

   Plan the switch ahead of time. Deciding roughly how many weeks you'll run a phase before you start makes it easier to stop on purpose instead of drifting.

None of this needs to be exact. A phase that runs a bit short or a bit long isn't a disaster. What matters more is noticing when a cut or bulk has stopped doing its job, and being willing to call it and move into the next phase, or a stretch at maintenance, instead of just carrying on out of habit.