You’ve likely heard people grumble about struggling to shed pounds because of a sluggish metabolism. Or those who eat sparingly but still put on weight. Perhaps they intentionally measure themselves against slender individuals who seem to indulge without consequence.
In reality, for most individuals, excess weight isn’t typically a result of a slow metabolism, thyroid issues, or some mysterious external factor beyond their control.
The fundamental principle for weight loss is straightforward: consume fewer calories than your daily energy expenditure, maintaining a negative energy balance. Now, where does metabolism fit into this equation?
WHAT IS METABOLISM?
Metabolism encompasses a series of chemical reactions in the body that generate the energy necessary for life.
Human metabolism includes various aspects collectively responsible for daily energy expenditure: basal metabolism, the thermogenic effect of food, and daily activities along with physical exercise.
Basal Metabolism (Resting Metabolic Rate)
Basal metabolism is the energy your body requires at rest to initiate all biochemical and physiological processes, contributing to about 70% of daily energy expenditure.
To illustrate, picture your body as a car engine. When you’re asleep or at rest, your body is akin to a car at a traffic light—stationary but still using some fuel to keep the engine running. Even at rest, there’s a basal energy expenditure sourced from the calories in the food we eat or those stored for later use.
Resting metabolic rate hinges on factors like weight, body composition, age, and gender. Notably, fat-free mass, especially skeletal muscle, plays a vital role since it is metabolically active.
THE THERMIC EFFECT OF FOOD
The thermic effect of food denotes the energy required for the entire digestive process, from digestion and absorption to transport, metabolism, and nutrient storage. This process consumes around 10% of the daily caloric value.
Protein intake, found in meat, fish, eggs, legumes, and dairy products, has the greatest thermal effect, contributing to about 20 to 30%. In contrast, fat intake has a smaller effect, ranging from 0 to 3%.
DAILY ACTIVITIES AND EXERCISE
All activities beyond rest involve energy expenditure, varying based on each individual’s degree and daily activity. This includes programmed exercise and day-to-day activities like chewing, sitting, standing, and walking.
In weight loss programs, this dimension contributes to increased caloric expenditure, aiding in the necessary energy deficit.
IS SLOW METABOLISM A BARRIER TO WEIGHT LOSS?
In weight loss, the crucial factor is energy intake, which must be lower than total daily energy expenditure, irrespective of one’s metabolism type.
Contrary to common belief, obese individuals generally have a higher metabolic rate due to more weight, fat mass, and fat-free mass. However, they often underreport their intake, distorting actual caloric intake.
A fast metabolism implies needing more calories to maintain weight. This explains why some people can consume more without gaining weight. Conversely, a slow metabolism burns fewer calories at rest and during activity, necessitating eating less to avoid gaining weight.
HOW TO OPTIMIZE METABOLISM FOR WEIGHT LOSS
While energy expenditure isn’t entirely within an individual’s control, energy consumption is a personal choice. Besides food choices, there are ways to enhance a slow metabolism:
- Increase daily physical activity to boost energy expenditure—walk more, use stairs, avoid prolonged sitting, and choose enjoyable exercises.
- Have small, frequent meals to avoid extended periods without eating.
- Ensure sufficient and quality sleep; a poor night’s sleep increases hunger perception and caloric intake.
Despite claims, there’s no scientific evidence supporting the idea of foods or supplements significantly increasing metabolic rate.