For some, increasing BMI is as physically and psychologically challenging as weight loss is for others. A BMI below 18.5 is clinically defined as underweight, often signaling nutrient deficiencies or metabolic issues. In this guide, we detail how to increase BMI through clinical weight-gain protocols that prioritize health over 'dirty' mass gaining.
1. Why Increasing BMI Matters
Being chronically underweight is associated with osteoporosis, hormonal imbalances, and a weakened immune system. A study published in the Lancet Diabetes & Endocrinology revealed that individuals at the low end of the BMI scale have as higher mortality risk than those in the overweight category.
2. The Calorie Surplus Protocol
To increase mass, your body must be in an Anabolic (building) state. This requires consuming more calories than you burn. A target surplus of **300-500 calories per day** is generally recommended for lean mass gain without excessive fat accumulation.
Use our BMR Calculator to determine your basal needs before adding your surplus.
3. Macronutrient Composition
Macronutrient balance is non-negotiable for healthy weight gain. Focus on High-Quality Protein (minimum 1.6g per kg) to repair and build muscle, Healthy Fats (Avocados, Nuts) for calorie density, and Complex Carbohydrates to fuel your training sessions.
4. The Role of Resistance Training
Simply eating more will increase BMI by adding fat. However, to increase BMI **safely and functionally**, engaging in heavy resistance training is imperative. The progressive overload principle triggers muscle hypertrophy, which adds dense, metabolically active weight to your frame.
Common FAQ
Is 'dirty bulking' okay to increase BMI?
No. While consuming large amounts of low-quality, high-sugar foods will increase BMI, it can lead to metabolic dysfunction, insulin resistance, and increased visceral fat. High-density, nutrient-rich foods are always the superior choice.