Dr Giles Yeo brings something different to weight-loss and dieting.

He isn’t pushing an eating plan. Instead, through his research, broadcasting and his book Gene Eating, he’s providing a more biological dimension to consider when wondering why we all vary so much in size.

Giles is an obesity geneticist. His career is devoted to studying the control of bodyweight - trying to understand what role our genes play, as well as how those genes respond to environmental factors, like stress and the foods we are surrounded by.

“I’m interested in why - in this current environment that we live in; what we call the obesogenic environment - are some people obese, some people overweight, some people average and some people skinny as anything,” he told me.

So while you and I might be used to thinking about body fat as something controlled purely by lifestyle choices, Giles reminds us that a person’s weight-loss battle is actually being influenced by factors out of their control.

Because of this, he is judged negatively by some who perceive him to be giving overweight people “an excuse,” he told me in HealthHackers episode 29.

Giles explained how - as a result of our DNA - some of us are always going to feel hungrier than others and find it harder to resist temptation when trying to cut back on food.

He explained that there are over 200 known genes that influence our behaviour around food - and there are probably more.

According to Giles, it’s the number of those genes we each have that decides whether we become fat or skinny - because they pretty much modulate our ability to say no to food. 

“Obesity, while it might seem a simple problem because we appear to have a choice, if it’s more difficult for us to say “no” because of our genes, then it is not really a choice,” he told me.

This isn’t helped by the fact that our brains hate it when we lose weight; believing it means we don’t have enough food, therefore our survival must be under threat.

It prompts the body to slowdown metabolism slightly and causes us to feel more hungry, he explained.

“Then you yo-yo diet and the weight comes back up.

“It’s very depressing… I’m just giving you the biology.”

But if you suspect your genes are driving you to eat more, what do you do?

Giles called this “the 64 million dollar question” - and explained that one of the problems to fixing obesity is our food-abundant environment.

“Not only are we eating more yet getting less nutrients we are also now, on top of that, adding a toxic discussion around food and I think that’s a bad thing,” he says. 

“We should be loving our food, we should just be eating less of the food we that we love - I think that is the answer.”

It’s probably not what you wanted to read really though, is it?

“There is no other way of losing weight aside from eating less and moving more… at the end of the day you have to do that,” he told me.

I asked about the people who try their hardest to eat less and exercise more but say it simply didn’t work. He suggests one potential reason for this could be a result of how “efficient” their body is at burning calories.

“There are going to be some who eat exactly the same amount… but will weigh differently.”

I suggest, surely, this means they really can blame their genes for being overweight.

“Blame is such a strong word,” he said.

“Does it strongly, strongly influence the way we end up being? Yes it does.”

If biology isn’t on our side for achieving weightless - there’s always surgery, right?

Hold up. 

Giles told me liposuction can increase your risk of developing type 2 diabetes, heart disease, certain cancers, and Alzheimer’s.

It’s all to do with your genetically determined “safe fat cell capacity,” you see. He likened it to a reservoir of fat being stored safely by your body. If the fat spills over capacity it can affect parts of your body where fat shouldn’t be and therefore puts you at risk of illness.

We all have different sized reservoirs.

“Which is why you have skinny people that become type 2 diabetic… they have a very small safe fat carrying capacity,” he said. 

And if you are someone who opts for liposuction - a process that removes fat cells - you are making your reservoir smaller, increasing your chances of having an overspill when you put on weight.

“Yes, you may have a gorgeous booty… you may look great but [you] have increased your chances of dying,” he told me.

Perhaps this quote from Giles’ book, Gene Eating, will bring this article to an appropriate and realistic end.

“Weight loss is difficult, it is hard. Our biology makes it hard. So you shouldn’t feel bad if it feels hard, because it ain’t s’posed to be easy. What you have to do is to chip away at it a little at a time…”

Follow Giles on Twitter and Instagram.

Watch HealthHackers episode 29 and also see Giles discuss his TV investigation into supplements; whether we need them and which ones could actually be dangerous for us. 

Thanks to London’s Royal Institution for having us to film this episode.