Reverse dieting
Raising calories gradually after a diet, aiming to limit fat regain on the way back up.
Reverse dieting is the practice of increasing calories gradually after a diet, typically by a small amount each week, with the aim of returning to maintenance without regaining fat.
The idea it is usually sold with, that this rebuilds a damaged metabolism, overstates the case considerably. Metabolic adaptation is real but modest in ordinary dieting, and expenditure returns towards normal largely as bodyweight and food intake return towards normal rather than because of the schedule you used.
The genuine benefits are behavioural and practical. A structured increase gives a person coming off a long diet a plan instead of a cliff edge, allows appetite and training performance to recover in a controlled way, and prevents the common pattern of finishing a diet and immediately overshooting.
There is also a real measurement problem it helps with. Weight rises when calories go up regardless of fat gain, because glycogen and its associated water and food volume all increase, and a gradual approach makes it easier to distinguish that from actual regain.
Its cost is time. Adding calories very slowly can keep someone in a semi-restricted state for months after a diet has ended, which is not obviously better than returning to maintenance over a couple of weeks and getting on with training.
For most people the middle ground works: increase to estimated maintenance over two to four weeks, hold there, and watch the weekly average rather than adding fifty calories a week for six months.
In practice, use our TDEE calculator to estimate the target you are reversing towards, and treat the process as a transition plan rather than a metabolic repair.