Is It In Your Genes?
Have you ever wondered why some people gain weight very easily and others can eat all they want and not gain an ounce? Please read a previous post entitled “Born to Be Fat?” Click here.
Ethan Sims of the University of Vermont studied prisoners at a nearby state prison who volunteered to gain weight. They succeeded with great difficulty to increase their weights on average by 20-25% and it took 4-6 months.
Some consumed 10,000 calories/day and once fat, their metabolisms increased by 50% When the study ended, the prisoners had no trouble losing weight. Within months, they were back to normal and kept their weights stable.
These results suggest that there is a reason that overweight people cannot stay thin after they diet and that thin people cannot stay fat when forced to gain weight. The body’s metabolism speeds up or slows down to keep weight within a narrow range.
Recently, some new research adds more insights about how our DNA is involved. Here are some highlights:
Researchers deleted a gene called MRAP2 in mice that acts in the brain and controls how quickly calories are burned. It turned out that this gene helped another gene known to control appetite. These animals ate the same amount of calories as lean mice, but gained weight.
They also found a mutation in the same gene in a severely obese child and are now searching for other mutations that have the same or similar effects. If the gene that was helped to control appetite was not controlled by the helper gene (MRAP2), then the animals developed tremendous appetites, gained the weight without eating more calories and the weight resulted in fat accumulation.
People are often blamed for their own lack of self-control over eating or that they do not exercise, but in some people this is just not the case.
Researchers based at University College London reported that a specific form of a gene previously linked to obesity, FTO, could increase craving for high-fat foods. This gene makes an appetite hormone named ghrelin that works on the brain’s pleasure center to make high calorie foods more appetizing and desirable.
In this study, the researchers divided a group of 359 healthy men of normal weight by their FTO gene makeup. The majority of the men had low-risk versions of the gene, while 45 of the participants had mutations that have been linked to greater appetite and caloric consumption. They then measured levels of ghrelin both before and after meals that the participants ate. The men with the low-risk form of FTO showed a significant drop in ghrelin levels after the meals that signified that they were full while the men with the mutated form did not show this effect.
It is thought that about 70% of obesity causes are genetically controlled but that environmental influence on the genes can certainly occur.
The results did not mean that people are completely helpless to control their weight, but it does appear that people who tend to be overweight have a greater battle with their genes if they want to lose weight and maintain that weight loss.
As stated before, body weight is so highly regulated by so many physiological and psychological factors with many body systems involved, especially the brain. Maybe in the next few years or so, we can begin to figure out what actually causes weight gain and that it’s not just gluttony and lack of self-control. All these studies are valuable pieces of the puzzle.