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Diets, fat burning foods, and supplements are often touted as solutions for weight loss. However, many people mistakenly believe that their slow metabolism is the reason for their inability to lose weight, and they think that weight loss is only possible if their metabolism is accelerated. Despite the lack of evidence to support this claim, doctors have repeatedly had to address the harmful consequences of people attempting to artificially speed up their metabolism. The goal is to investigate whether it is possible to regulate metabolism and whether doing so would be beneficial.
What is metabolism?
The body requires energy and building material for various functions such as heartbeat, breathing, and blood circulation. To obtain these resources, the body converts the food and drinks we consume into energy and building material through a process called metabolism. All living organisms, including bacteria and plants, have a metabolic process.
The energy content of food is measured in calories, while the building material is referred to as nutrients. Nutrients include proteins, fats, carbohydrates, vitamins, and minerals.
Metabolism is a complex biochemical process in which enzymes break down food molecules into compounds that the body requires, and energy is released. These molecules then enter the Krebs cycle, a sequence of chemical reactions that facilitate the conversion of molecules into necessary compounds and energy.
The metabolic rate is not a conscious process and cannot be intentionally altered. Hormones from various glands such as the thyroid, pancreas, adrenal, ovaries, and pituitary glands regulate it.
In a healthy person, the metabolism maintains a balance between energy consumption and expenditure. If the metabolic reactions are faster or slower than usual, hormones compensate for the acceleration or slowdown by affecting other areas of the body.
If there is an energy imbalance, a physician will look for possible underlying issues and prescribe hormonal replacement therapy to compensate. For example, individuals with hypothyroidism, a condition where the thyroid gland does not produce enough hormones that increase the metabolic rate, require such treatment.
Even if the molecules within the Krebs cycle could be made to function faster, it would not result in weight loss. The cycle’s primary function is to convert food into energy and building materials, and even if the body quickly transforms rice into energy, it will still be stored as a reserve.
When do you need to contact an endocrinologist?
Excessive body weight can sometimes indicate disruptions in the endocrine system related to specific hormones. In such cases, in addition to weight gain, the person may experience other health issues.
For instance, a thyroid gland disorder can cause fatigue, dry skin, muscle pain, and irregular menstrual cycles. To rule out a thyroid gland pathology, a physician will order a thyroid-stimulating hormone (TSH) test. If the TSH concentration in the blood is normal, then the weight gain is not due to thyroid gland dysfunction.
Do metabolic boosters work?
Speeding up metabolism with a diet, special foods, or supplements is a myth. The rate at which food turns into energy and nutrients cannot be changed by regular exercise, celery, or dietary supplements.
Diet
There is no scientific basis for the theory that eating just a little bit will speed up metabolism. Studies have shown that individuals who ate frequently, up to six times a day, did not experience weight loss and often felt hungry. On the other hand, those who ate once a day did not gain weight or experience discomfort. As a result, eating frequency does not have an impact on metabolism, and individuals can eat as often as they feel comfortable.
“Fat burning” products.
Green tea, grapefruit, or red hot peppers do not boost metabolism. While they may briefly increase the thermic effect of food, which refers to the number of calories the body uses to digest food, this increase is insignificant compared to the total amount of calories the body expends to maintain daily physiological processes. Therefore, consuming these foods does not have a significant impact on weight.
Dietary supplements
Most metabolic drugs are pacifiers and contain microdoses of vitamins, plants, or extracts that act as a placebo. For instance, garcinia cambogia, chitosan, chromium picolinate, pyruvate, and glucomannan have not demonstrated any effect on metabolic rate or weight loss.
In addition to useless plant extracts, some dietary supplements may contain diuretics or laxatives, such as senna extract. Although a person might believe they have lost weight, only water has been excreted, which quickly returns to its original volume.
It is important to note that supplements can also be both dangerous and ineffective. For instance, supplements containing the psychoactive substance ephedrine have been associated with heart attacks, strokes, and sudden death, leading to their ban in the United States and limited circulation in other countries.
Dietary supplements are not subjected to the same rigorous control as drugs, so it is impossible to be certain that they do not contain harmful substances. For instance, a study of 52 caffeinated dietary supplements found that 28 samples contained sibutramine (a prescription drug that should only be taken under medical supervision), phenolphthalein (a laxative that can be harmful to health), and psychotropic substances such as amfepramone and fenproporex.
If the supplements affect the thyroid gland, the situation can be even worse. Since thyroid hormones regulate metabolism, these supplements can increase metabolism. However, such intervention can result in thyroid gland diseases. In the United States, the drug Triax had this mechanism of action and has been banned for sale for over two decades. Any dietary supplement may contain these substances since they are not subject to strict control.
Metabolism and weight gain
When discussing accelerated or slow metabolism, people often refer to weight loss or weight gain. However, in most cases, weight loss or gain is due to a calorie deficit or surplus, not metabolic rate. Unlike the speed of the biochemical process, this parameter can be altered by the individual.
The majority of the calories we consume each day are used by the body to carry out vital functions such as respiration, heartbeat, hormone production, cell growth, and repair. This is the minimal and unconscious expenditure. Another 5-10% of calories are used for digesting food, while the remaining 20% of calories are utilized for physical activity.
Organ weight and the amount of energy used by it
| % of body weight | % of the energy required | |
| Muscle | 40% | 20% |
| Adipose tissue | 31% | 3% |
| Liver | 2.6% | 19% |
| Brain | 2.0% | 17% |
| Digestive system | 1.7% | 10% |
| Heart | 0.5% | 8% |
| Kidneys | 0.4% | 7% |
| Rest | 31% | 16% |
When there is a surplus of calories, the body stores the excess in reserve, while in the case of a deficit, the body utilizes these reserves. Our body is a clever machine that stores reserves during an excess of calories and spends them when there is a deficiency.
Initially, the extra calories are stored in the form of bound together glucose molecules known as glycogen, of which there is about 100 grams available in the body. The liver stores it for nourishing the brain and central nervous system. The rest of the excess calories are stored in the form of adipose tissue, and there is no limit to the amount of adipose tissue that can accumulate in the body.
Adequate Caloric Intake for an Average Person
Both men and women require an average of 2000 to 2500 calories for basic expenditure, digestion, and physical activity. These figures are based on individuals with average parameters, such as women who weigh 57 kg and stand 163 cm tall, and men who weigh 70 kg and stand 178 cm tall. Although everyone is different, some individuals may find 2000-2500 kcal per day to be sufficient, excessive, or inadequate. Lifestyle and individual characteristics, including gender, age, weight, height, and muscle mass, can influence calorie requirements.
Weight and height
Calorie needs increase with a person’s size. For instance, if an individual weighing 70 kg and standing 178 cm tall requires 2500 calories per day, then 2500 calories would be excessive for someone weighing 55 kg and standing 165 cm tall.
Muscle mass
Muscles require nearly twice as many calories as body fat, meaning individuals with less muscle require fewer calories than those with the same weight but more muscle.
Gender
In general, men require more calories than women because they possess more muscle mass and less fat.
Age
As people age, their muscle tissue typically decreases while their fat tissue increases, leading to a reduced need for calories. For instance, the same 2500 kilocalories required at the age of 20 would be excessive at the age of 60.
Special formulas can be employed to estimate the approximate number of calories an individual requires. While several formulas exist, the American Dietetic Association regards the Mifflin-St. Jeor equation as the most precise. It factors in various lifestyle and individual parameters, such as weight, height, muscle mass, gender, and age.
The Case Against Counting Calories Forever
To stay healthy, it is not necessary to constantly count calories. A person without hormonal problems needs to maintain physical activity, establish a sleep routine, eat balanced and enjoyable meals, relying on hunger and satiety cues. This will be enough to prevent weight from fluctuating unpredictably.
None of the leading global nutrition organizations recommend counting calories for everyone without exception. It is only one of the tools to reduce weight. However, regularly recording and weighing every meal is an unhealthy relationship with food. Endless calorie counting and food weighing can trigger eating disorders – illnesses in which a person cannot control their eating habits. For example, they may eat too little due to the fear of gaining weight, then give in to cravings and overeat. Such eating habits ultimately harm health.
Eating disorders are a type of mental disorder, and it is often difficult to deal with them alone, so the help of specialists such as a psychotherapist, dietician, or endocrinologist may be required.
Physical activity and weight loss
Daily physical activity accounts for roughly 20% of all calories expended, with the majority coming from common everyday actions such as walking, cleaning, and shopping. These activities can expend up to 800 kcal per day, which is two to three times more than typical gym workouts. Therefore, incorporating more physical activity into everyday life can be just as advantageous as working out at the gym three times a week while being inactive the rest of the time.
The lack of everyday physical activity is a contributing factor to obesity. The World Health Organization (WHO) recommends 150 to 300 minutes of moderate-intensity activity per week, which equates to about 22 minutes of brisk walking per day. The more we move, the more calories we burn, and the better equipped we are to prevent obesity.
Food consumption and weight loss
To maintain weight, one simply needs to avoid exceeding their necessary calorie intake. However, to lose weight, it is necessary to create a calorie deficit by consuming less than what is expended. This leads to the body burning reserves from adipose tissue, resulting in weight loss. Scientists recommend a small deficit of up to 700 kilocalories per day to achieve slow and steady weight loss without negative health consequences.
Although it is commonly believed that fast food should be eliminated from the diet for weight loss, the reality is that even with the most unhealthy food choices, weight loss can be achieved with a calorie deficit. Nevertheless, unhealthy food with an abundance of sweet, fatty, and salty dishes poses a risk factor for diabetes, ischemia, and other diseases. Thus, limiting fast food in the diet is necessary not just for weight loss, but also for disease prevention.
The optimal diet is a balanced one that includes all five food groups: vegetables and fruits, complex carbohydrates, fats, proteins, and dairy products. Scientists recommend following the plate rule, where half of the meal should consist of vegetables and fruits, a quarter of proteins, and the remaining quarter of carbohydrates.
One should avoid going to extremes when trying to consume fewer calories. Lowering calorie intake below the body’s basic requirements will cause weight loss to stop. If calorie intake is excessively low, the body will break down muscles to sustain vital functions. This will result in a decrease in muscle mass, leading to fewer calories burned by the body. Upon returning to an adequate calorie intake, the body will begin to gain fat mass because it is burning fewer calories than before the diet.
Sleep and weight loss
Evidence suggests that obesity risks may increase due to insomnia and other sleep disorders. The reasons for this are not yet fully understood by scientists. It is possible that individuals with insomnia tend to eat at night, or that the increased stress resulting from lack of sleep causes some to overeat.
Despite the lack of a precise understanding of how sleep affects weight, one can still minimize the potential risk of weight gain by prioritizing healthy and high-quality sleep.
Sources:
- How Food Frequency Affects Weight – American Journal of Clinical Nutrition
- Review of Nutritional Supplements for Weight Loss – American Journal of Clinical Nutrition
- Sleep and Metabolism Relationship – International Journal of Endocrinology
- The President and Fellows of Harvard College – How sweet the drinks are?
- Low Fat versus High Fat Diet Comparison – American Journal of Clinical Nutrition
- The link between consumption of ultra-processed foods and mortality – British Medical Journal
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