Research

Energy balance

Reducing daily energy intake or increasing physical activity by approximately 100 kcal/day is sufficient to prevent population-wide weight gain and arrest the obesity epidemic.

To stop gaining weight, you do not need to overhaul your life. Aim to create a 100-calorie daily deficit. You can achieve this by walking one extra mile (about 15-20 minutes) each day, or by simply eating three fewer bites at each meal. These small, sustainable adjustments are enough to counteract the environmental pressures causing weight gain for most people.

ModerateSupportsMEDIUM confidence
Using data from national surveys, we estimate that affecting energy balance by 100 kilocalories per day (by a combination of reductions in energy intake and increases in physical activity) could prevent weight gain in most of the population.
James O. Hill et al. · Science · 2003

Why this rating

Based on retrospective epidemiological data (NHANES/CARDIA) and theoretical modeling, not a randomized controlled trial of the specific 100 kcal intervention.

Source

Obesity and the Environment: Where Do We Go from Here?

James O. Hill et al. · Science · 2003

DOI 10.1126/science.1079857

narrative_reviewCited 2,198×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →