Simple Physiology of Weight Loss


Weight loss is an evergreen fashion trend, for centuries the cosmetic world has thrived on our innate tendency to be lighter by a few kilos on the devilish weighing scale, and to appear younger by a few years.

Motivated by several reasons like; trying to improve health, a cautious attempt at preventing illness, rehabilitation, peer pressure, social acceptability etc. However the tendency to lose weight sees an inordinate rise in proximity to a special or social event.

So what really is the science behind weight loss? Is everyone cut out to be super-skinny? Let’s look at a rough dissection of the physiology of weight loss. Considering an ideal condition the consumed food is used up as fuel for the basal metabolism, basic body functions and physical activity. Anything more than this is stored as fat for later use if required. Maintaining a steady weight is a collective work of homeostatic (bodily), environmental and behavioural factors influencing each other.

Homeostatic factors: a combination of neuro-hormonal system regulates body weight. The hypothalamus controls hormones related to appetite regulation, and processes signals that convey information of food intake and energy balance. Where there is a biofeedback loop between the brain and digestive organs, muscles and fat. Along with this there is yet another pathway called “hedonic” associated with palatability (sight, smell and taste) of food. Interestingly, this hedonic pathway can easily override the normal feedback increasing the desire to consume foods high in energy, even if the body is physiologically satiated and the required energy is met with, simply because it provides pleasure from eating.

Environmental factors: the environment shapes one greatly, and now we dwell in an “obesogenic” environment. Production and marketing of high energy foods, easy and increased availability of the same, disproportionate serving sizes, all of this gradually pushes us into consumption of more energy/ calories than required, social gatherings are dominated with food intake, desk jobs and gadgets leave very less room for physical activity. Not to forget undue stress ( on society as a whole), erratic work hours and sleep deprivation etc.

Behavioral factors: the mind is the master of all, the body follows the way one behaves. With all the knowledge about weight loss, healthy diet and exercise, one will not lose even a fraction of a pound if not put into action. One needs to change their behaviour in regard to exercise and food. Family and friends are obviously the best support system, but sometimes such individuals may need to undergo behaviour therapy to be able to break their tendencies.

Everyone’s body is unique, with different shapes and sizes which is dependent on multiple factors, like genes, eating patterns, hormones, exercise and Resting Energy expenditure (REE).

Weight loss is the result of a deficit between one’s total energy intake and total energy expenditure, in simple terms burn more calories than one consumes. Very mundane basic functions of the body (like; cell development, pumping of the heart, maintain body temperature, breathing) also use up calories, infact somewhere near 50- 70% of it. This energy or calories that the body uses for its vital functioning is the Resting Energy expenditure or REE.

REE in turn is determined by one’s age, gender, genetic composition, skeletal structure or frame and the body composition. In this light it looks like one’s calorie burn up is predetermined like destiny! But that’s the catch!.. very similar to how our actions affect the outcomes, the amount of calories burnt also is affected by the physical exertion or exercise one engages in.

Rome was not built in a day, Safe weight reduction demands time and effort, aiming for safe weight loss one should be looking at reducing somewhere between 1-2 pounds per week. One pound converts into 3,500 calories, meaning that it is required to burn/ reduce about 500 calories per day. But simply deciding on going through a grueling workout and eating a restricted/ certain type of food (no-carbohydrate, high protein, liquid diets) is not the answer, as it will only result in weight- regain because of the negative loop it puts one in. Such an attitude is highly potential of inducing eating disorders or related issues.

Honoring a healthy relationship with one’s own body, it is best to practice a healthy, nutritious eating pattern and incorporating physical exercise to suit one’s lifestyle and interest for long time goals of losing weight and henceforth maintain it.

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