Macronutrients and Calorie Requirements

Section: Health | Vida Vertical

Summary

An adequate intake of energy and macronutrients forms the foundation of any evidence-based nutrition plan. This article explains the physiological basis of energy requirements, distinguishes between basal and activity energy expenditure, and presents common formulas for estimating individual calorie needs. It then examines the three macronutrient groups—protein, fat and carbohydrates—in terms of their biochemical functions, energy density and needs-based intake. A worked example illustrates the method in practice. The final section considers how a plant-based food supply from controlled cultivation can support the quality of macronutrient intake.

1. Introduction

Macronutrients—protein, fat and carbohydrates—are far more than mere energy sources. They perform key structural, regulatory and metabolic functions in the human body. Protein provides building material for muscle, skin and nerve cells; fats contribute to hormone synthesis and cell-membrane integrity; carbohydrates are the preferred energy source for the central nervous system and skeletal muscles.

Individual nutrition planning therefore requires two steps: determining personal calorie requirements and deriving a goal-oriented macronutrient distribution from them.

2. Calorie Requirements: Basal and Activity Energy Expenditure

A person’s daily energy expenditure consists of two components:

2.1 Basal Metabolic Rate

Basal metabolic rate is the amount of energy the body requires under strict resting conditions to maintain vital metabolic and organ functions. It is measured at complete physical rest, under thermoneutral conditions and 12 to 14 hours after the last food intake to exclude distorting effects from diet-induced thermogenesis.

The simplified calculation formulas are:

• Men: 1 kcal × 24 h × body weight (kg) = basal metabolic rate (kcal/day)
• Women: 0.9 kcal × 24 h × body weight (kg) = basal metabolic rate (kcal/day)

Basal metabolic rate is determined primarily by height, body weight, age and sex and can barely be influenced in the short term.

2.2 Activity Energy Expenditure

Activity energy expenditure comprises the energy used through physical and mental activity in addition to basal metabolism. It is the principal source of individual variation in calorie expenditure and can be actively increased through movement and exercise.

Activity energy expenditure is quantified using PAL values (Physical Activity Level), which represent a person’s activity profile:

2.3 Total Energy Requirement

Daily calorie requirements are calculated by multiplication:

Total energy requirement = basal metabolic rate × PAL value

Example calculation:A 75 kg man with an office job who exercises three times per week:

• Basal metabolic rate: 1 kcal × 24 h × 75 kg = 1,800 kcal/day
• PAL value (office job + regular exercise): 1.7
• Total energy requirement: 1,800 kcal × 1.7 = 3,060 kcal/day

3. Macronutrients: Functions and Intake Recommendations

3.1 Protein

Energy density: 4.1 kcal per gram

Proteins consist of chains formed from around 20 different amino acids. They act as signalling molecules in metabolic processes, structural components and contractile units in muscle. Protein is indispensable for building and repairing muscle, skin and nerve cells (Lemon, 2000).

Intake recommendations:

Higher protein intake during a calorie-restricted phase supports muscle retention and reduces the loss of fat-free mass (Helms et al., 2014; Helms et al., 2015).

3.2 Fat

Energy density: 9.3 kcal per gram

Fat is the most energy-dense macronutrient. Its physiological functions include:

• Energy storage (an evolutionary reserve function)
• Synthesis of hormones, including sex hormones
• A structural role as a component of cell membranes (insulating function)
• Enabling the absorption of fat-soluble vitamins (A, D, E and K)

A high fat intake does not in itself cause weight gain; overall energy balance is decisive. Nevertheless, fat intake should be kept moderate, particularly during a calorie-restricted diet, to preserve calories for protein and carbohydrates.

Intake recommendations:

A sustained intake below 0.5 g/kg body weight should be avoided because hormone production—particularly that of sex hormones—may be impaired.

3.3 Carbohydrates

Energy density: 4.1 kcal per gram

Carbohydrates are the only non-essential macronutrient because the body can synthesise glucose from protein and fat through gluconeogenesis. Nevertheless, they are highly relevant to physical and cognitive performance.

Carbohydrates are classified by chain length: short-chain sugars are absorbed rapidly, while long-chain starches, such as those in potatoes and wholegrain products, require enzymatic breakdown. The resulting glucose contributes to blood-glucose regulation, immediate energy provision and glycogen storage in skeletal muscle.

Adequate carbohydrate intake is crucial for athletes to maintain training intensity and working loads (Horswill et al., 1990; Leveritt & Abernethy, 1999).

Calculation: Carbohydrate intake is the remaining amount after the calorie contributions of protein and fat have been set.

4. Practical Example: Macronutrient Distribution for Muscle Gain

Result: 160 g protein, 80 g fat and 439 g carbohydrates at a total intake of 3,200 kcal.

The sequence of the method is:

1. Determine calorie requirements (basal metabolic rate × PAL value).
2. Define the objective (muscle gain: surplus; fat loss: deficit).
3. Set the protein amount (g/kg body weight).
4. Set the fat amount (g/kg body weight).
5. Allocate the remaining calories to carbohydrates.

5. Energy Balance and Objectives

Energy balance is the foundation of every nutrition plan:

• Muscle gain: A calorie surplus of 200 to 400 kcal above maintenance.
• Fat loss: A calorie deficit of 300 to 500 kcal below maintenance.

Without deliberately modifying energy balance, neither substantial muscle gain nor meaningful fat loss can be achieved. Macronutrient distribution determines how body composition changes, whereas energy balance determines whether body weight changes.

6. Relevance to Plant-Based Food Provision: The Role of Controlled Cultivation

For Vida Vertical readers, one further aspect deserves emphasis: the quality of macronutrient intake depends directly on the nutrient composition of the foods consumed. In vertical growing systems and hydroponic or aquaponic facilities, crop nutrition can be controlled precisely. Leafy vegetables, herbs and legumes from controlled cultivation can be particularly rich in protein and minerals when the nutrient solution is optimally balanced.

Short intervals between harvest and consumption, typical of vertical self-provisioning, preserve nutrient integrity and minimise storage and transport losses. In practical terms, people who cultivate their own sources of protein and carbohydrates—such as legumes, leafy vegetables or potatoes—can directly influence freshness and nutrient density.

7. Conclusion

Calculating individual calorie requirements and distributing macronutrients according to a specific objective is not a one-off task but an iterative process. The method presented here—determining basal metabolic rate, assigning a PAL value, setting protein and fat by body weight, and calculating carbohydrates as the remainder—provides an evidence-based framework suitable for the broad majority of health- and fitness-oriented adults. Individual adjustments for training status, metabolic characteristics and personal objectives may still be necessary.

A considered energy balance, needs-based macronutrient distribution and high-quality foods that are as fresh as possible together form the foundation of a sustainable dietary strategy—whether the food comes from a supermarket or your own vertical garden.

Note: These recommendations apply to healthy adults without underlying metabolic disease. Individual advice from a qualified nutrition or medical professional is indicated in the presence of illness, during pregnancy or breastfeeding, or when taking medication.

References:

• Helms, E. R., et al. (2014). A Systematic Review of Dietary Protein During Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes. International Journal of Sport Nutrition and Exercise Metabolism, 24(2), 127–138.
• Helms, E. R., et al. (2015). High-protein, low-fat, short-term diet results in less stress and fatigue than moderate-protein moderate-fat diet during weight loss in male weightlifters: a pilot study. International Journal of Sport Nutrition and Exercise Metabolism, 25(2), 163–170.
• Horswill, C. A., et al. (1990). Weight loss, dietary carbohydrate modifications, and high intensity physical performance. Medicine & Science in Sports & Exercise, 22(4), 470–476.
• Lemon, P. W. (2000). Beyond the zone: Protein needs of active individuals. Journal of the American College of Nutrition, 19(suppl 5), 513S–521S.
• Leveritt, M. & Abernethy, P. J. (1999). Effects of Carbohydrate Restriction on Strength Performance. Journal of Strength and Conditioning Research, 13(1), 52–57.
• German Nutrition Society (DGE): D-A-CH reference values for nutrient intake. www.dge.de

Author: Uwe | Vida Vertical – Health