“From as long as you can remember, ‘they’ have always existed. They were always there to show what you could never be. Here you were struggling and their very existence seemed to poke fun at you. You never thought you could be friends with them but now some of your very good friends are thin and skinny. The kind that loves food and hogs everything that you crave for yet cannot eat. When you here are trying to make ‘healthy’ choices they are stuffing their mouths with second helpings of the rice and gorging on the delicious pastries. Thin and skinny people seem alright if they starve and diet but those who eat even more than you and still lack a pound of fat around them, are really annoying”….
There have been countless studies telling why some people are obese and how to overcome obesity with exercise and diet but there has been very little written about the fact that some people don’t gain weight irrespective of how much or what they eat. We should know why some people don’t gain weight as much we know why most of us, do. This article is an attempt in understanding why some thin people remain that way…
What do Genes have to do with it?
A lot, some experts say. Dr. Albert Stunkard, University of Pennsylvania studied 450 adopted children most of whom were adopted at a very younger age, to observe whether inheritance or environment plays a bigger a part in determining weight. The study showed that the adoptees were as fat as their biological parents with no relation with the weight of the adopted parents.
In another study Dr. Stunkard conducted studying pairs of identical and fraternal twins, where he found that most identical twins weighed more less the same, irrespective of whether they were raised together or apart. Thus he concluded that 70% of weight variations are inherited.
The ‘Natural’ weight
According to Dr Rudy Leibel of Columbia University everyone has a natural weight which is biologically determined and our bodies try to maintain this weight. He explains that it is like a thermostat with all bodies having a set point, if the body’s weight goes beyond a point; the body tries to get back to the original weight.
In an experiment conducted by BBC’s Horizon 10 skinny people were put on a high calorie diet (with foods like chocolates, ice creams, cheese cakes, puddings, high fat chips etc.) for 4 weeks with restrictions on activities. Four weeks later, their fat levels were checked. The researchers found that while some participants gained about 7-15 % of their body weight, others gained very little. The researchers also noted that once the participants resumed their regular life, most of them lost all the additional weight without extra efforts.
Two of the participants in the study could not eat their excess diet as they would soon gag and vomit most of the contents. Their bodies resisted this extra consumption of food than required and they could not complete the daily allocation of food. There was also one participant who gained weight but had no significant change in his appearance, further investigation showed that he had not gained any extra fat but had increased the muscle mass in his body, his basal metabolic rate or the rate of calories burnt by the body while resting, grew by a whopping 30%. Thus in spite of the increase in food intake, his body managed to burn most it.
It proves the theory that body recognizes a natural weight and tries to stick to it no matter what. This also explains why subjects in another study by Rockefeller University Hospital, who lost around 100 pounds over 8 months, regained all back. A study into their metabolic activity showed that their metabolism rates slowed down as their brains believed they were in the starvation modes, storing more fat and burning very little.
Metabolic Level
In this same study in the Rockefeller University, these subjects showed they burned equal number of calories as a normal person before they began dieting but after months of dieting, they started burning calories at 24% lower rate than before. This made it difficult for them to lose weight and brought them back to their original weight as before without eating as much.
Growth Hormone
While the most common advice to lose weight is “Eat lesser calories than you burn”, what do you say when people eating the same amount of food and with same activity levels have different levels of fat deposition? In an experiment two rats given same amount of food had different levels of fat deposited in their bodies, the determining factor was the levels of growth hormone in their body. Thus it is assumed that those with higher levels of growth hormone are resistant to weight gain. This also explains why as we grow old and have lower levels of growth hormone, we start gaining weight. However it is also true that with exercise you can stimulate secretion of growth hormone and maintain your weight.
‘No’ when they are full
Another factor that scientists believe determines our weight is a gene called FTO. Those with one variant of this gene weigh more than others and find it difficult to know when they are full. Hence they tend to eat even when they are not hungry. Others who lacked this gene, could easily refuse food when they were full and thus did not need to exert any will power to just say ‘no’.
Muscle mass
Another reason that skinny people stayed that way is the muscle mass in their body. Instead of depositing fat, one subject in the BBC experiment showed increased muscles mass after 4 weeks of eating the most fattening food. More of muscle mass means more of weight loss, as muscles require more metabolic energy to sustain hence they tend to burn more calories overall. It is another example of how the body tries to maintain the normal weight.
If all the studies and research quoted in the article discourages you, remember that genes and metabolism play a role in determing your weight but even these can be overcome with efforts on your side. These studies on the other hand, also break myths regarding obesity like overeating is the root cause; we now know that weight is determined not just by how much you eat but also by your metabolism and genes. Thus, we will be more sensitive to those who are genetically predisposed to being obese and are struggling to lose weight.
