AFAA Personal Trainer Certification 2025 – 400 Free Practice Questions to Pass the Exam

The factor that significantly impacts resting metabolic rate is a high percentage of lean body mass. Lean body mass includes muscles, bones, and organs, which are metabolically active tissues that require energy to maintain. The more lean mass a person has, the higher their resting metabolic rate, meaning they burn more calories at rest. This is because muscle tissue is more metabolically demanding than fat tissue; therefore, individuals with greater muscle mass will naturally utilize more energy, leading to an increased metabolic rate.

High body fat percentage, low carbohydrate intake, and frequent weight fluctuations do not promote an increase in metabolic rate in the same way. A higher body fat percentage tends to correlate with a lower metabolic rate. Additionally, while carbohydrate intake plays a role in overall energy balance and macronutrient distribution, it is the amount of lean body mass that primarily contributes to metabolic rate. Frequent weight fluctuations can also negatively affect metabolism over time, as they may lead to muscle loss, further reducing the resting metabolic rate.