Energy balance

Preventing excessive population-level weight gain requires closing a small daily 'energy gap' (e.g., 10-30 kcal/day) through sustainable small behavior changes rather than large, difficult-to-maintain interventions.

To prevent gaining weight, you don't need to overhaul your life. You only need to reduce your daily energy intake or increase expenditure by a tiny amount (e.g., 10-30 calories, roughly one small bite of food or a few minutes of walking). This small, sustainable change is enough to stop gradual weight gain for most adults, whereas trying to lose existing weight requires much larger, harder-to-keep efforts.