Weigh loss refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other connective tissue).
Calorie expenditure is composed of the following three major components
- Resting metabolic rate (RMR). Thie number of calories your body needs to maintain normal bodily functions, such as breathing and pumping blood.
- Thermic effect of food (TEF). the calories used to digest, absorb, and metabolize food.
- Thermic effect of activity (TEA). These are the calories you use during exercise. TEA can also include non-exercise activity thermogenesis (NEAT), which accounts for the calories used for activities like yard work and fidgeting.
Factors affecting weight loss
- Gender: since women typically have a greater fat-to-muscle ratio than men, they have a 5–10% lower RMR than men of the same height. Your fat-to-muscle ratio greatly affects your ability to lose weight.This means that women generally burn 5–10% fewer calories than men at rest. Thus, men tend to lose weight quicker than women following a diet equal in calories.
- Age: the body composition starts to change during aging fat mass increases and muscle mass decreases, this change, along with other factors like the declining calorie needs of your major organs, contributes to a lower RMR.this decrease in RMR can make weight loss increasingly difficult with aging..
- Calorie deficit Starting to cut off some food and counting your calories that you eat with how much calories you expend during the day will help you losing weight
For example, consuming 500 fewer calories per day for 8 weeks will result in greater weight loss than eating 200 fewer calories per day with the same physical activity.
Make sure Not to deficit to large amount of calories.
- Sleep: Sleeplessness affects hunger hormone levels, increasing ghrelin, which makes you feel hungry, and decreasing leptin, which makes you feel full
Ghrelin is a hormone released in the stomach that signals hunger in the brain. Levels are high before you eat, which is when the stomach is empty, and low after you eat. Leptin is a hormone released from fat cells. It suppresses hunger and signals fullness in the brain
Poor sleep negatively affect the sympathetic nervous system, resulting in increased levels of cortisol — a hormone related to stress
It may also suppress various hormones, such as levels of insulin-like growth factor 1 (IGF-1). IGF-1 is linked to greater fat storage.
-Physical activity: more physical activity increases the number of calories your body uses for energy or “burns off.” The burning of calories through physical activity, combined with reducing the number of calories you eat, creates a “calorie deficit” that results in weight loss.
Several other factors can affect your weight loss rate, including:
- Medications. Many medications, such as antidepressants and other antipsychotics, can promote weight gain or hinder weight loss also cortisone is a medicine that increases body weight and fluids.
- Medical conditions. Illnesses, physiological conditions including depression and hypothyroidism, a condition in which your thyroid gland produces too few metabolism-regulating hormones, can slow weight loss and encourage weight gain,.
- Family history and genes. genetic component associated with people who have overweight or obesity.
- Wrong diet Yo-yo dieting and highly restricted caloric diet: This pattern of losing and regaining weight wrong diet and highly restricted calories diet can make weight loss increasingly difficult with each attempt, due to a decrease in RMR.
1- Sumithran, Priya; Proietto, Joseph (2013). "The defence of body weight: A physiological basis for weight regain after weight loss". Clinical Science. 124(4): 231–41. doi:10.1042/CS20120223. PMID 23126426.
2- Hankey, Catherine (23 November 2017). Advanced Nutrition and Dietetics in Obesity. John Wiley & Sons. pp. 179–181. ISBN 9781118857977.