Calorie-restriction

Multiple dietary patterns produce weight loss when they create a calorie deficit. The DIETFITS trial showed no superiority of any macronutrient pattern at 12 months. This article reviews the evidence for the most commonly used weight loss diet approaches.

Constipation is a common side effect of calorie-restricted and low-carbohydrate diets. This article explains why it occurs mechanistically, which dietary approaches are most likely to cause it, and evidence-based interventions that address the causes.

Liu et al. (2022, NEJM, n=139, 12 months) found time-restricted eating (8-hour window, 16:8) produces equivalent weight loss to matched calorie restriction. Intermittent fasting works primarily through spontaneous calorie reduction, not metabolic rate changes. The 16:8, 5:2, and alternate-day fasting methods are reviewed with their evidence.

Approximately 70–80% of weight loss is determined by diet rather than exercise in controlled trials. The most evidence-supported diet-only strategies are protein increase (+440 kcal/day spontaneous reduction), ultra-processed food reduction (+500 kcal/day reduction), and calorie tracking. This article covers what works without exercise.