Registered dietitian and acredited Nutritionist
Our body is mainly made up of water, protein and fat. Exercice and diet can influence the proportion of each of these elements. Body weight is made up of lean body mass (organs, skin, bones, body water, and muscle mass) and fat mass. The lean body mass is divided (for a subject of normal corpulence) into:
Based on this information it becomes clearer why the weight measured by a scale is not a reliable indicator for evaluating weight gain or loss. Weight loss can be the result of muscle, water or fat loss, usually it is a combination of all three. To follow the evolution of a weight loss, it is necessary to measure the body composition and see the evolution of your fat mass and muscle mass over time. It is important that the percentage of your muscle mass stabilizes or increases and that the percentage of your fat mass decreases. A dietician or dietitian-nutritionist generally has devices that measure body composition accurately.
Fat is stored in cells called adipocytes or adipose cells. Losing body fat does not reduce the number of these fat cells but rather reduce their volume. During weight gain the volume of these cells will increase and when it has reached 40 to 50% of its initial volume these cells are likely to multiply, a phenomenon which is irreversible.
In a normal state, energy intake via food is used as energy to operate the organs (breathing, heartbeat, …), for food digestion (protein digestion consumes the most energy) and physical activities.
All excess energy is stored in the form of fat into fat cells for later use. Normal body weight is influenced by a number of different factors. These factors fall into three distinct but interrelated categories: homeostatic, environmental and behavioral processes.
Homeostasis: state of internal equilibrium of an organism in the face of changes in the external environment.
Body weight is regulated by a complex neuro-hormonal system, which reflects the fundamental biological importance of energy balance and nutrient supply.
The signals involved in the homeostatic regulation of food intake, energy balance and body weight emanate from the brain. A number of neuropeptides and hormones involved in appetite regulation act on the brain by stimulating or suppressing hunger. The brain also processes peripheral signals that convey information about short-term food intake (i.e. nutrient availability) or long-term energy balance (i.e. energy stores) to achieve energy homeostasis. The brain also integrates 'hedonic' (pleasure-related) reward pathway signals associated with craving (eg, sight, smell, and taste) for food. Such hedonic reward pathways can override the homeostatic system and increase the desire to consume energy-dense foods, despite physiological satiety and full energy stores.
The environment in which we live greatly influences energy homeostasis. This environment is characterized by intense marketing of energy-dense foods,an increased availability of these foods and an increase in portion size, all, offering people the opportunity to overconsume portions of sugary, high-fat foods. Moreover, a society where stress is a daily occurrence stimulates compensatory food intake. This increase in food intake is accompanied by a decrease in physical activity, for example due to sedentary jobs and a decline in the promotion of physical education in schools. Other factors that can influence weight are: infection, epigenetics, increased maternal age, higher fertility in obese and overweight people, assortative mating, lack of sleep, endocrine disruptors, pharmaceutical iatrogenesis and reduction of ambient temperature variability.
Our behavior also influences our energy balance. It is obvious that simply knowing that a healthy diet and exercise will lead to weight loss is not enough to achieve and maintain a healthy lifestyle and reduce excess body weight. Personal motivation for change can play a fundamental role in altering unhealthy habits and lifestyles. With the help of a dietitian-nutritionist, you will gradually overcome the difficulties of adaptation and adopt a healthy lifestyle.
Chronic stress : When you're experiencing anxiety, stress, or grief, your body can produce chemicals — like the hormone cortisol — that make your body more likely to store fat, especially around your waistline. Cortisol is a hormone naturally produced by your body. Created by the adrenal glands located on your kidneys, cortisol is released when you are stressed. This sends your body into fight or flight mode, temporarily interrupting regular bodily functions and slowing down your metabolism. Cortisol boosts your fat and carbohydrate metabolism, creating a surge of energy in your body. While this process is essential for survival situations, it also increases your appetite. Additionally, high cortisol levels can cause cravings for sweet, fatty, and salty foods. This means you're more likely to indulge in fries and a milkshake than a well-balanced meal.
Excess cortisol can also cause your body to produce less testosterone. This can lead to a decrease in muscle mass and slow down the number of calories your body burns.
Although lowering your stress levels may seem impossible on some days, you can still manage the effects of high cortisol levels. For starters, practicing relaxation, meditation, yoga, or deep breathing can help bring the production of this hormone back to normal levels.
Try to eat mostly whole, plant-based foods. Of course, making the decision to eat well isn't always easy, but it's worth the effort. By watching your diet, the calories you consume will be turned into energy, not converted into fat and stored by the body.
Finally, exercise is also a great way to manage your stress hormones. Whether you go out for a run, take a daily walk with your family, or hit the gym, exercise will help you maintain lean body mass. This is especially important during prolonged periods of high cortisol levels.
Hypothyroidism : Body composition and thyroid hormone seem to be closely linked. Thyroid hormones regulate basal metabolism, thermogenesis and play an important role in lipid and glucose metabolism, food intake and fat oxidation. Thyroid dysfunction is associated with changes in body weight and composition, body temperature, and total energy expenditure and resting energy expenditure independent of physical activity.
Hypothyroidism is associated with decreased thermogenesis, decreased metabolic rate and has also been shown to correlate with higher body mass index (BMI) and higher prevalence of obesity. There is clinical evidence to suggest that even mild thyroid dysfunction in the form of subclinical hypothyroidism is linked to significant changes in body weight and represents a risk factor for overweight and obesity; however, this remains a gray area.
Depression : Many depressed people turn to food to relieve their emotional distress.
Menopause and hormonal changes in women : Menopause is a stage in a woman's life during which the risk of gaining weight is very high. Weight gain associated with menopause is due to low estrogen levels following a gradual loss of ovarian function. Additionally, changes in hormonal milieu, advancing age and decline in physical activity coupled with a westernized diet, and recurrent episodes of emotional eating associated with psychological distress also contribute to increased total body fat and waist circumference. A larger waist circumference is an independent risk factor for cardiovascular and metabolic disease in postmenopausal women.
Estrogen and progesterone are the main female sex hormones and play a vital role in regulating appetite, eating behaviors and energy metabolism. The balance between these hormones can impact fat loss and health.
The continued depletion of follicular ovarian reserve during the menopausal transition decreases estrogen production with a relative increase in androgen levels. This hormonal imbalance alters energy homeostasis by regulating hunger and satiety signals. Estrogen inhibits the action of hunger signals, preventing the phenomena of excessive consumption of calories. Postmenopausal women experience more intense hunger cues encouraging increased food intake which promotes weight gain.
The hormonal imbalance during menopause also promotes the significant accumulation of fat in the abdominal region. Low levels of estrogen along with high levels of androgens lead to a redistribution of fat present in the gluteal and femoral regions to the abdominal regions of the body, thereby promoting abdominal obesity.
Aging : In fact, as we age, we tend to gain weight as a result of muscle loss, hormonal change, slower metabolism, more sedentary and sometimes more stressful lifestyles, and major lifestyle changes. .
The amount of muscle naturally begins to decrease by 3 to 8 percent per decade after age 30. You can also lose muscle if you are less active due to age-related health issues, such as arthritis, bed rest from injury, or surgery for several days. Why is this loss of muscle important? Because muscle uses more calories than fat.
Both men and women experience changes in hormone levels as part of aging. In women, menopause - which most often occurs between the ages of 45 and 55 - leads to a significant drop in estrogen which encourages extra pounds to settle around the belly. Men, on the other hand, experience a significant drop in testosterone as they age, which begins to gradually decline around age 40 at a rate of about 1-2% per year. Testosterone is responsible, among other things, for regulating fat distribution and muscle strength and mass. In other words, decreasing it can make the body less efficient at burning calories. As you age, it's harder for your body to build and maintain muscle, which, in turn, also impacts the number of calories you burn.
By the time you hit your 40s and 50s, your career is probably in full swing, which, while great, can cause some weight loss issues. For one thing, you're probably moving less. You can go to work for about an hour, sit at a desk for eight or more hours a day, and have so much on your plate that there's no time for a walk or a workout. exercise during the working day.
Increased water intake is associated with loss of body weight produced by two mechanisms, decreased feeding and increased lipolysis (the breakdown of fats and other lipids by hydrolysis to release amino acids). Mild but chronic hypohydration (little drinking) is correlated with increased body weight and subsequent dysfunction. Drinking 0.5 liters of water can increase the amount of calories burned for at least an hour. Drinking water before meals can reduce appetite in middle-aged and older people, which results in reduced calorie intake, leading to weight loss. Drinking more water can lead to a decrease in caloric intake and reduce the risk of long-term weight gain and obesity, especially in children.