Okay, we all know the basics: eat less and move more, right? On average we now eat a couple of hundred more calories a day than previous generations did, so that does need fixing. But research is also showing why losing weight really is harder for some people than for others.
The problem seems to be that the messages telling our bodies what to eat, when to eat it and how much to eat can become distorted. So how can we take back control?
Your appetite hormones
Hormones are the body’s chemical messengers, and researchers, including the obesity team at Imperial College London, have found that some of the answers lie with two hormones made in the gut that work together to control appetite and weight:
- Ghrelin, the hunger hormone, rises before meals and tells your brain it’s time to eat.
- PYY, a fullness hormone, rises after eating and tells your brain you’ve had enough.
Your gut is constantly talking to your brain, saying “stop eating” or “eat more”. When you skip meals, these hormones and your willpower start to fight each other. You become distracted, grumpy and indecisive, and when you’re really hungry, food is all you can think about.
In many people of a healthy weight, these hormones rise and fall as they should around meals. In some people living with obesity, the fullness signal after a meal is weaker, so they don’t feel full even after a large meal. It’s not simply a lack of willpower; it’s willpower against hormones, which is why it can be so difficult.
Biology, willpower and epigenetics
It’s long been believed that willpower is the main reason some people stay slim. But research into epigenetics, the study of how our environment and lifestyle switch genes on and off, shows other factors play a part, such as high stress early in life and diet before and after birth.
The good news? Many of these changes can be influenced by what we do now.
Exercise changes how your fat cells work
In a study published in PLOS Genetics, researchers at Lund University in Sweden, led by Dr Charlotte Ling, recruited 23 slightly overweight, inactive men in their 30s and 40s. After six months of weekly spin and aerobics classes, without other changes to their diets or daily lives, the men were fitter and had lost weight.
More interesting were biopsies of their fat tissue. They showed changes in DNA methylation, a chemical “switch” that can silence genes, in more than 7,000 genes, including several previously linked with type 2 diabetes, metabolic syndrome and obesity. In other words, exercise changed how the men’s fat cells were programmed. The study was small and the individual changes were modest, but it adds to evidence that exercise benefits the body well beyond the kilojoules it burns. (Read the BioNews report on the study.)
Early diet can have lasting effects
A mother’s diet during pregnancy and what a baby is fed in early life can cause changes that last into adulthood. Animal studies have shown that a lack of the methyl-donating nutrients folate and choline late in pregnancy or soon after birth can leave parts of the genome under-methylated for life. In adults, a diet low in these nutrients also reduces DNA methylation, but the changes reverse when a normal diet is resumed.
What this means for you
- Eat regular meals built around protein, fibre and vegetables, which help your fullness hormones do their job.
- Move your body regularly; exercise helps in ways that go beyond weight.
- Eat folate-rich leafy greens and legumes and choline-rich eggs, and if you’re planning a pregnancy, talk to your GP about a folic acid supplement.
- Be kind to yourself. If losing weight feels harder for you than for others, it may well be, so ask your GP or a dietitian for support.
This article is general information about food and wellbeing, not medical advice. Please talk to your GP or a qualified health professional about any health condition, medication or major change to your diet.
