Why weight loss is so hard

By Anshvardhan Shetty

Losing weight may appear straightforward but in reality, it is rather challenging. Many who attempt to lose weight are unsuccessful or gain their weight back. It’s not just the late-night pizza and the lack of exercise that prevents weight loss though - in fact, our bodies actively fight back against weight loss. Analysing how our bodies react to shedding fat can explain why so many people struggle. All over our body we have a connective tissue that consists of lipid-rich cells (adipocytes) that stores energy, known scientifically as adipose tissue but more commonly recognized as body fat (2). Your body can use this energy-rich substance to fuel your cells; it acts as reinforcement if your body requires extra energy or needs to carry out metabolic reactions. A popular strategy for weight loss is to try and force your body to burn this fat for energy, reasoning that once your weight-loss goal is achieved you can revert to your original lifestyle.

However, your body is resistant to losing its extra energy supply. When you restrict your diet by cutting calories it has negative side effects that make it harder to lose weight. Leptin, a hormone produced by your adipocytes, alters your food intake and your energy expenditure in order to maintain your current conditions (3). The larger your fat cells are, i.e., the more body fat you have, the more leptin is produced and losing weight causes your leptin levels to drop. (1)

Your hormone secretion is controlled by the hypothalamus located at the rear of the brain (4). A lack of leptin is interpreted as starvation, so the hypothalamus signals the body

to restrict the amount of energy burned and to eat more to rebuild the energy reserves. Your organs also notify the brain of starvation: the stomach alerts the brain that it is not being filled by increasing the levels of ghrelin, causing you to have a larger appetite and overeat. Ghrelin is a hormone created by enteroendocrine cells which are found in the alimentary canal, they produce and release hormones to regulate how hungry you feel. (5) Simultaneously, your pancreas secretes less insulin, which regulates your blood sugar levels causing high blood glucose levels, and less amylin, which signals fullness therefore causing you to carry on eating. This hormonal change increases your appetite, your cravings, and the pleasure you receive after submitting to these cravings. (1) Your body also becomes more energy efficient since it tries to limit the energy used and relies more heavily on glucose solely from foods instead of from a mix of glucose and body fat for energy (1). This results in a lower resting metabolic rate (a measure of the number of calories burned at rest), as well as a decrease in fat loss.

What’s worst is that even after you stop restricting yourself your hormonal starvation signal continues, which is why most weight losses aren’t sustainable. Your brain still thinks you are starving even if you gain your weight back. Generally, we believe that the smaller you are the less fuel you need, but it also depends upon your past and whether you’ve been heavier or thinner before. In 2016, the televised weight loss competition “The Biggest Loser” studied 14 contestants and their weight loss journeys. After 30 weeks, the participants lost a mean of 58kg as well as seeing their resting metabolic rates decreased by approximately 610kcal/day. over the course of the competition. However, in the years after, they gained back an average of 41 kg but without their metabolic rates increasing, leaving them burning 500 kcal less per day than they should be at their final weights. (1)

The next time they attempt weight loss they will be restricted further and further. Those who have lost weight previously are at a disadvantage to those who have never been heavier or lighter since these people are maintaining a constant weight and will therefore eat less overall (comparative to body mass). But for those that have lost weight before, consuming a regular intake of food would ultimately increase their mass because of the discussed roles of leptin, the hypothalamus, ghrelin etc.

However, losing weight gradually at a safe rate of 0.5-1 kg each week deceives our body into thinking we’re eating normally (6). Phillip Stanforth, a professor of exercise science at the University of Texas, states, “That typically means you’re losing a few pounds a week. And that tends to be a lot more sustainable than losing a whole bunch at once.” Moreover, Mayo Clinic’s Dr. Donald D. Hensrud writes, “The concern with fast weight loss is that it usually takes extraordinary efforts in diet and exercise — efforts that could be unhealthy and that you probably can’t maintain as permanent lifestyle changes.” (7) In conclusion, your body doesn’t like too much change at once. A gradual decrease in weight is more beneficial for you both mentally and physically – the solution is sustainability.

References

1. SciShow (Director). (2019). The Real Reason It’s So Hard to Lose Weight [Motion Picture]. 2. Adipose tissue. (2018, Febuary). Retrieved from You and Your Hormones: https://www.yourhormones.info/glands/ adipose-tissue/ 3. Leptin. (2018, March). Retrieved from You and your Hormones: https://www.yourhormones.info/hormones/leptin/ 4. Boeree, D. C. (2002, 2009). The Emotional Nervous System. Retrieved from The Limbic System: http://webspace. ship.edu/cgboer/limbicsystem.html 5. Metab, M. (2015, June). Ghrelin. Retrieved from US National Library of Medicine National Institutes of Health: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443295/ 6. (2019, November 29). Start the NHS weight loss plan. Retrieved from NHS: https://www.nhs.uk/live-well/ healthy-weight/start-the-nhs-weight-loss-plan/ 7. Brodwin, E. (2016, Jan 6). How many pounds should I lose each week? Retrieved from Business Insider: https://www. businessinsider.com/how-many-pounds-should-i-lose-each-week2016-1?r=US&IR=T