Genetics and Weight: Why Some People Struggle More Than Others

If you've ever wondered why some people seem to be able to eat whatever they like and stay slim whilst you struggle to lose weight despite your best efforts, the answer may partly lie in your genes. Research has identified numerous genes that influence body weight, appetite regulation, and metabolism. Studies done on twins suggest that genetic factors account for 40 to 70 percent of the variation in body weight between individuals.

This doesn't mean that weight is predetermined by genetics, but it does mean that some people face a steeper uphill battle when it comes to weight management. Some people inherit variations in genes that affect leptin, the hormone that signals fullness, or ghrelin, the hormone that signals hunger, or the efficiency of their metabolism. Others may have genetic differences that affect how their bodies store and use fat, or how sensitive they are to the rewarding properties of food.

The FTO gene, sometimes called the 'fat gene', is one of the most studied genetic variants associated with obesity. People who carry certain versions of this gene tend to have higher BMIs and may feel less satisfied after eating, leading them to consume more calories before feeling full. If you've always felt that you needed to eat more than others to feel satisfied, this might be part of the explanation.

However, genetics isn't destiny. While you can't change your genes, you can influence how they're expressed through your lifestyle choices. This is where the emerging field of epigenetics becomes relevant, showing how environmental factors can influence which genes are 'turned on' or 'turned off'. Your genes load the gun, but your environment pulls the trigger.

Beyond genetics, numerous hormones play crucial roles in weight regulation. Insulin resistance, for example, can make weight loss extremely difficult. When cells become resistant to insulin, the body produces more insulin to compensate. High insulin levels promote fat storage and make it harder to access stored fat for energy. This creates a biological environment that favours weight gain and makes weight loss feel like fighting against your own physiology.

Understanding that there are genuine biological differences in how people's bodies regulate weight can be incredibly liberating. It helps explain why simple advice like 'just eat less' can feel so frustratingly inadequate. It's not about willpower or moral failing. Some people genuinely do have bodies that are more resistant to weight loss.

This is also why GLP-1 medications can be so transformative for people who have struggled despite genuine efforts. These medications work at the biological level, addressing some of the hormonal and neurological factors that make weight management so difficult. They help level the playing field for people whose genetics have stacked the odds against them, offering a real chance to finally achieve lasting change.