Fat

The science behind losing and gaining fat

Parts of this page:

  • Introduction
  • Types of body fat 
  • Hormones & Fat Regulation
  • How to lose fat
  • Metabolism & Energy Expenditure
  • Fat Distribution & Genetics
  • How to gain fat
  • Long-Term Fat Maintenance

*Disclaimer: This page shares general, science-based information about fat. Results vary depending on genetics, hormones, and lifestyle. For personalized guidance or medical conditions, consult a qualified healthcare professional.

Introduction

Fat isn’t just “extra weight.” Your body actually needs it. Fat stores energy, protects your organs, helps regulate hormones, and even supports brain function. The problem starts when fat — especially the kind stored deep around your belly — builds up too much. That’s why understanding fat, and how to manage it, is important for both health and appearance.

Types of Body Fat

  • Subcutaneous Fat: Found under the skin. This is the most visible type and usually less dangerous.

  • Visceral Fat: Stored around organs in the abdomen. Linked to heart disease, diabetes, and metabolic syndrome.

  • Brown Fat: Burns calories to generate heat. Mostly present in babies, but still exists in small amounts in adults.

  • White Fat: Stores energy and makes up most of body fat. Excessive storage leads to overweight and obesity.

Hormones & Fat Regulation

Fat gain and loss aren’t only about calories — hormones play a big role:

  • Insulin: Helps store glucose as fat when there’s a calorie surplus, especially from high-carb diets.

  • Leptin: Signals satiety (fullness). Resistance can lead to overeating.

  • Ghrelin: Stimulates hunger, often rising before meals.

  • Cortisol: The stress hormone. Chronically high cortisol can lead to belly fat storage.

Balancing hormones through sleep, stress reduction, and a balanced diet makes fat management easier.

How to Lose Fat

    1. Calorie Deficit → Eat fewer calories than you burn.

    2. More Protein, Fewer Sugary Carbs → Protein keeps you full and helps preserve muscle.

    3. Cut Trans Fat & Fructose → These encourage fat storage and poor health.

    4. Exercise (Weights + Cardio) → Strength training keeps muscle; cardio adds extra calorie burn.

    5. Lower Stress → High cortisol = stubborn belly fat.

    6. Sleep Well → 7–9 hours keeps hunger hormones in check.

Metabolism & Energy Expenditure

Your total calorie burn is made of:

  • BMR (Basal Metabolic Rate) → Energy used at rest (~60–70% of daily burn).

  • NEAT (Non-Exercise Activity Thermogenesis) → Walking, fidgeting, standing. Small movements add up.

  • TEF (Thermic Effect of Food) → Energy used to digest food. Protein burns more calories than carbs or fats.

  • Exercise Activity → Workouts and sports.

Boosting NEAT and protein intake can make fat loss more efficient without extreme dieting.

Fat Distribution & Genetics

  • Genetics decide whether you store more fat in the belly, hips, or thighs.

  • Hormones influence shape too:

    • Estrogen promotes fat around hips and thighs.

    • Testosterone promotes muscle and less fat storage.

  • You can’t “spot reduce” fat, but overall fat loss eventually reduces stubborn areas.

How to Gain Fat

Not everyone wants to lose fat. Some people may need to gain fat in a healthy way:

    • Eat more calories than you burn, but don’t rely on junk food.

    • Use healthy fats (nuts, avocado, olive oil, fatty fish).

    • Keep eating protein so you gain more lean mass, not just fat.

    • Strength train to balance fat gain with muscle growth.

Long-Term Fat Maintenance

The hardest part isn’t losing fat — it’s keeping it off. Crash diets usually backfire. Instead:

  • Build habits you can stick with.

  • Stay consistent with both food and exercise.

  • Focus on body composition (more muscle, less unhealthy fat), not just scale weight.

Resources / Further Reading

Hall, K.D. et al. (2012). Energy balance and its components: implications for body weight regulation. American Journal of Clinical Nutrition.

Bray, G.A. et al. (2017). Consumption of added sugars and development of obesity and metabolic syndrome. Circulation.

Rosen, E.D. & Spiegelman, B.M. (2014). What we talk about when we talk about fat. Cell.

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