With all of us spending more time in isolation and possibly consuming a higher than normal volume of food, I thought I would discuss energy requirements for maintaining a healthy weight.

Carbohydrates, proteins, fat, and alcohol are all sources of energy. When these nutrients are consumed, digested, absorbed, and metabolized, the energy becomes available for use by the body. The energy is either used immediately, or stored for future use. The scientifically correct terms for the measurement of energy are Calorie (capitalized) or kilocalorie, but in this article, I will use the more commonly used term, calorie.

For many people, the term calorie carries a negative connotation because it brings to mind weight gain. Rather, people should think of energy and calories as positive terms, as energy is needed to fuel activity. People who do not take in sufficient energy run the risk of consuming too few nutrients. However, excess energy intake over time is also not desirable because of the impact of excessive body fat on general health.

My clients often ask, “How many calories do I need?” Unfortunately, there’s no simple answer to this question. Many factors influence energy balance, including age, gender, body composition, metabolic rate, tissue growth, and the intensity and duration of activity. The general energy needs of different groups of people also vary. For example, sedentary adults, recreational athletes, and children may require drastically different quantities of various nutrients.

Since every person is different, we can’t know the exact energy requirements for any individual. Still, various texts can provide reasonable guidelines for daily energy intake needed to maintain body weight. Simply put, however, if you are gaining body-fat, you are consuming too many calories.

Exercise also plays an important role in determining one’s energy requirements, and the intensity and duration of exercise must be considered when fine-tuning general recommendations.

When discussing athletics, the sport-specific requirements must also be considered. Sports such as baseball do not require a high-energy expenditure, while other sports, such as professional basketball and distance cycling, are extremely high-energy sports.

Training also varies within a sport. Professional and elite amateur athletes train at greater intensity, volume, and/or duration than others in the same sport. Endurance athletes expend a large amount of energy in their daily training and in the performance of their sport. Distance cyclists and triathletes may need energy intake well in excess of 50 calories per kilogram of body weight per day to maintain body composition. However, some endurance athletes, such as distance runners, restrict energy intake in an effort to attain or maintain a low percentage of body fat.

While it may be advantageous in distance running to be a low percentage of body fat (extra body fat increases body mass but not power), it is a disadvantage if the athlete does not consume enough energy to fuel training, maintain muscle mass, and receive an adequate amount of nutrients.

Athletes who engage in “stop and go” sports such as basketball or soccer may also need a high-calorie intake to match the long hours of training and the demands of competition. Soccer players may cover 8 to 12 km (~ 5 to 7 miles) during the course of a game, although they are not running continuously.

Strength-focused athletes also may need a large amount of energy. For example, male bodybuilders perform resistance training for several hours each day, and the energy needed to support their large amount of muscle mass is substantial. On the other hand, bodybuilders may reduce energy intake to 30 calories per kilogram of body weight per day as they prepare for a contest and try to reduce body fat. Wrestlers’ energy intake may be reduced in an effort to make a particular weight category.

Energy intake likely changes over the course of the pre-season, competitive season, and post-season. The general guidelines must be refined to meet the athletes’ goals, considering the demands of their sport. Adjustments are made for age, gender, extent of muscle mass, rate of metabolism, muscle growth, and the intensity and duration of exercise. For example, a 35-year-old female who is maintaining muscle mass and whose metabolic rate is beginning to slow will require less energy than a 20-year-old female who is increasing muscle mass and likely has a higher resting metabolic rate. Each individual must determine the caloric intake that maintains current body composition.

Meeting, while not exceeding, energy needs should be a top priority for all people. Those who chronically consume too little energy often consume too few nutrients, which leads to poor health. People with daily energy intakes near the bottom end of the guidelines should be particularly cautious. More commonly, however, the average person consumes a large volume of low-quality food, thus exceeding caloric requirements while taking in too few nutrients. The way to avoid this is to consume a diet comprised of mainly fresh, whole foods that have not been processed. This would include fresh produce such as fruit, greens, and non-starchy vegetables. If you consume meat, try to stick with lean cuts of quality meat that does not have fillers or other additives and preservatives. Avoid food that comes in a box or has more than a few ingredients, as those foods are often overly processed. Last, if you are eating a quality diet but are still gaining weight, cut back on your portion sizes or increase your exercise to maintain a healthy bodyweight.