1. Missing Fat Enzyme
A digestive enzyme that determines how fat should be metabolised may be missing in skinny individuals, possibly allowing fat to simply pass through the body without weight gain.
2. Non-Exerxise Activity Thermogenesis (NEAT)
Simply fidgeting in your seat at work or standing up frequently can increase the output of energy, increasing your metabolic rate by as much as 50%.
3. Genetic Factors
Researchers discovered that a set of genes in chromosome-16 affects body weight, with those having double of this chromosome being skinny.
4. Medical Reasons For Thinness
Undiagnosed health conditions like hyperthyroidism, diabetes, and nutritional disorders can prevent weight gain and require medical attention.