Anyone who’s ever done it knows that losing weight is incredibly difficult. It often requires large overarching lifestyle changes, and is often characterized by a lot of setbacks. Still, why does it seem like some people find it easier to lose weight than others? Also, why does it sometimes feel like certain people are more predisposed to gain weight in the first place?
Researchers have been wondering these same things, and while this area of science is still relatively new, having taken off in the early 90s, we still know so much more today about weight gain and loss than ever before. Of course, environmental factors also play a huge role in someone’s weight. Overeating, lack of exercise, and overall unhealthy lifestyle choices have a larger impact on someone’s weight than genetics and hormones alone. But genetics also play a part in someone’s predisposition towards obesity, and hormones play a part in someone’s ability or inability to lose weight. What is still left to be discovered, is which genes and hormones are responsible.
Genetics
Generally speaking, researchers agree that genetic factors account for approximately 40 to 70 per cent of variance in the occurrence of obesity. Genetic obesity has three different classifications, monogenetic, polygenic, and syndromic. Of the three, polygenic is the most common, and essentially indicates that there are multiple genes working together to cause someone to be overweight. Monogenetic obesity is incredibly rare as it pinpoints only one gene causing someone to be overweight, and syndromic obesity means that a diagnosed medical condition, such as Prader-Willi syndrome, is causing someone to become overweight.
Through epigenetics, the study of how genes are expressed, around 250 genes have been identified to be associated with obesity. Of these, according to the report Genetics and Obesity published by National Institutes of Health, “the FTO gene on chromosome 16 is the most important and carries the highest risk of the obesity phenotype.” Of course, research is still ongoing, and so things like genetic testing cannot accurately predict whether or not someone will become overweight, and it is still unknown which combination of genes cause someone to become overweight, as this is often unique to the individual.
Researchers have also been exploring the developmental origins of health and disease hypothesis which suggests that maternal over and undereating can cause fetal programming towards obesity, and that paternal overeating also plays a role. Generally, there is a correlation between a person’s family medical history and their own weight. If a person’s family members are overweight or have struggled with their weight, it is likely that they will struggle too.
Hormones
There are a few hormones that have been identified in regard to weight management, leptin, estrogen, and androgens. Estrogen and androgens play a part in body fat distribution, with a drop in these hormones causing more body fat accumulation in the torso, which is more dangerous than on the extremities. Lack of estrogen can cause weight gain, and it has been found that women who take estrogen supplements during menopause are less likely to gain weight after menopause.
One of the most researched hormones into the cause of weight gain, however, is leptin. Leptin is produced by the fat cells of the body and reduces a person’s appetite. Leptin is a long-acting hormone, and does not fluctuate between meals, but rather, performs a careful balancing act long-term to help a person maintain a normal weight. In people who are overweight, their leptin levels are higher, but rather than working more strongly, this creates leptin resistance, which can cause the body to enter starvation mode. This causes a person to overeat after they are full and save calories, rather than releasing them while resting.
Also, according to the Cleveland Clinic, “Leptin has a more profound effect when you lose weight. As your body fat (adipose tissue) decreases, your leptin levels decrease, which signals your body to think that it’s starving. This stimulates intense hunger and appetite and can lead to increased food consumption.” Overall, it has been found that those who are overweight generally have hormone levels that encourage them to build and maintain body fat rather than shed it.
Lauren Schwartz | Staff Writer
