Metabolism and Genetics

Category: Health | Vida Vertical

Summary

The ideas of the “hardgainer”, who can apparently consume unlimited calories without gaining weight, and the “softgainer”, who supposedly accumulates fat after only a small calorie intake, remain widespread in fitness and nutrition circles. This discrepancy is often attributed wholesale to genetics or to a “fast” or “slow” metabolism. This article examines the physiological components of total human energy expenditure and evaluates the myth of genetic determination using evidence from sports science and metabolism. Genetically influenced variation in resting metabolic rate is relatively limited; major differences in calorie expenditure are more often driven by non-exercise activity thermogenesis (NEAT) and the thermic effect of food (TEF). It concludes by showing how maintaining aquaponic and hydroponic systems can naturally support these metabolic levers.

1. Introduction: the myth of genetic determination

The observation seems commonplace: some people eat large amounts without visibly accumulating fat, while others appear to gain weight merely by looking at energy-dense food. The popular explanation is a genetically predetermined fast or slow metabolism.

To evaluate this hypothesis scientifically, total human energy expenditure must be separated into its precise physiological components and genetic influences distinguished from lifestyle factors.

2. The four components of total energy expenditure

Total daily energy expenditure (TDEE) is not a single process but the sum of four distinct metabolic and mechanical components:

2.1 Resting Metabolic Rate (RMR)

RMR, often called basal metabolism, is the energy the body requires at complete rest to maintain vital organ function, cellular renewal and homeostasis. It is the component most strongly influenced by genetics, age, sex and body composition.

2.2 Thermic Effect of Food (TEF)

The thermic effect of food is the energy used by the gastrointestinal tract and cellular metabolism to digest, absorb and store macronutrients. Protein has the highest TEF at roughly 20–30 per cent of its energy content, while fat (2–3 per cent) and carbohydrate (5–10 per cent) incur substantially lower metabolic costs.

2.3 Thermic Effect of Activity (TEA)

This component covers deliberate energy expenditure through planned physical activity, such as resistance training, endurance exercise or purposeful physical work.

2.4 Non-Exercise Activity Thermogenesis (NEAT)

NEAT encompasses all unplanned, non-exercise activity in everyday life, including gesturing, fidgeting, maintaining posture while standing, walking to the car and general spontaneous movement.

3. The genetic factor: variation in RMR

Scientific studies of differences in resting metabolic rate (RMR) between individuals indicate that genetically influenced variation is only5 to 8 per cent.

For an average resting energy expenditure of 2,000 kcal per day, this means that 96 per cent of the population falls within a range of 1,700 to 2,300 kcal. The maximum genetic difference is therefore about 300 kcal—little more than the energy in two medium-sized bananas. For 70 per cent of people, variation is only about 150 kcal per day.

For the great majority of people, the belief that a “broken” or “slow” metabolism is the main cause of unwanted weight gain therefore lacks scientific support. Genuine metabolic disorders that substantially reduce energy expenditure, such as severe hypothyroidism, can be medically identified and affect only a small proportion of the population.

4. The lifestyle factor: NEAT and TEF as the real drivers

If genetics and RMR play only a limited role, what explains the large differences in daily energy expenditure? The answer lies in the combined contribution of NEAT, TEA and TEF.

A practical thought experiment illustrates this. Consider two people with identical biometric characteristics and resting metabolic rates who both complete structured resistance training four times a week (TEA). Their starting conditions appear equal.

• Person Aworks in a manual trade, moves throughout the day, fidgets frequently (high NEAT) and eats a protein-rich diet (high TEF).
• Person Bworks in an office, spends the evening passively on the sofa (low NEAT) and eats a diet rich in carbohydrate and fat (low TEF).

The combined effects of incidental daily movement (NEAT) and the metabolic cost of digestion (TEF) can create a difference of more than1,000 kcal per daybetween these two people. Person A can consequently eat substantially more without gaining fat and may mistakenly be labelled a “hardgainer” with “good genetics”. In reality, the difference reflects the cumulative effects of lifestyle and macronutrient choices.

5. Relevance to Vida Vertical: optimising metabolism through controlled cultivation

As a specialist in aquaponics and hydroponics, I view human metabolism in the context of our interaction with the environment and food production. Maintaining a vertical garden or aquaponic recirculating system offers useful synergies for the very metabolic factors that can distinguish stagnation from progress:

1. Integrating NEAT into everyday lifeCaring for a hydroponic or aquaponic system involves daily low-intensity routines: harvesting, checking water parameters, transplanting and cleaning components. These tasks interrupt prolonged sitting and add continuous incidental movement (NEAT) to daily life without feeling like exhausting exercise.

2. Maximising TEF with plant-based macronutrientsProtein and complex fibre structures increase the thermic effect of food. Legumes such as peas and beans, protein-rich microgreens and fibre-rich leafy vegetables grown in vertical systems provide a food matrix that takes more work to digest. Besides increasing diet-induced thermogenesis, the intact cellular structure of freshly harvested plants promotes lasting satiety and a steadier insulin response.

3. Avoiding metabolic dysfunctionHighly processed foods require less digestive processing and their highly palatable nature can encourage passive overconsumption. Fresh, unprocessed biomass from a home vertical farming system (NOVA group 1) engages chewing and the gastrointestinal tract in the work for which the human body evolved.

6. Conclusion

“Hardgainer” and “softgainer” are oversimplified concepts often used to explain insufficient daily movement and a suboptimal macronutrient balance. Genetics influences resting energy expenditure, but variation of only a few hundred calories is too small to explain weight problems by itself.

The key to metabolic control lies in deliberately influencing non-exercise activity thermogenesis (NEAT) and the thermic effect of food (TEF). Enriching daily life with active routines—such as maintaining an aquaponic or hydroponic system—and choosing nutrient-dense, minimally processed plant proteins provides practical control over energy balance. Metabolism is not a fixed genetic destiny but a dynamic system that responds to our environment and diet.

Note: This article provides general scientific information and does not replace individual medical diagnosis. Anyone who suspects a metabolic disorder, such as thyroid dysfunction, should seek medical assessment.

References:

• Levine, J. A. (2002). Non-exercise activity thermogenesis (NEAT). Best Practice & Research Clinical Endocrinology & Metabolism, 16(4), 679–702.
• Levine, J. A., et al. (1999). Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science, 283(5399), 212–214.
• Hall, K. D. (2010). Predicting metabolic adaptation, body weight change, and energy intake in humans. American Journal of Physiology-Endocrinology and Metabolism, 298(3), E449–E466.
• Westerterp, K. R. (2004). Diet induced thermogenesis. Nutrition & Metabolism, 1(1), 5.

Author: Uwe | Vida Vertical – Health