Why do people put on differing amounts of weight? – BBC News

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Foods that stimulate some of us put on weight can have little impact on others, according to research carried out under Israel. It might be time to rethink the way we diet, writes Dr Saleyha Ashan.

Like most of the population, I must admit that I am on an eternal quest to lose weight. For me it’s more to do with very concerned about health than aesthetics. I have polycystic ovary disorder and a family history of kind 2 diabetes and that sets me into a high risk category for developing diabetes myself.

I have always watched what I feed – and yet I never seem to change the weight, while friends seem to eat what they want without putting on a single protrusion. It seemed like they could just “break all the rules”. But perhaps that’s just because we have been incorrect about what “the rules” of diets are.

Last month, I travelled to Israel for Trust Me, I’m a Doctor to take part in a vast new research examine being carried out there by a squad at the Weizmann Institute of Science. They are in the process of monitoring 1,000 people in perfectly minute detail to see exactly how their bodies react to food – and their first results are rewriting the textbooks on our relations with food.

When we feed, our blood sugar level rises – and both the velocity at which it peaks, and then how quickly our bodies deal with that and get it back to normal, is very important to our health. Constant high spikes can lead to type 2 diabetes, as well as us laying down more fat and increasing our risk of other cancers.

Foods have, hence, been traditionally classified by how much of a blood sugar spike they cause – with “high GI”( Glycaemic Index) foods being thought of as bad for us, and “low GI” as good. Every nutritionist would tell you this. But the Israeli research, led by Dr Eran Segal and Dr Eran Elinav, suggests that it is simply not so.

Once I arrived in Tel Aviv, the team not only took all my vital statistics and medical history, but they gave me a little implanted glucose monitor under my skin, which would monitor my blood sugar levels constantly for the coming week. The team’s nutritional experts had prepared me six days of menus specifically designed to exam my body’s response to a few standardised snacks, mixed in with some of my own personal staple foods.

I’m an accident& emergency doctor, which is something that undoubtedly has an effect on my diet. Rushing around on my feet all day with strange running patterns has meant that eating hours can be erratic – and unless I have been super-organised, I am at the mercy of the hospital canteen.

I never buy bread – it’s an aisle I only don’t even go down in the supermarkets and I live in anxiety of sandwiches – but I find other people living on them.

I do, however, reach for the grapes – I love them. I can eat bunches of them and feel guilt-free doing so. They are my going to see “healthy” snack. Another guilt-free grab is sushi – especially after a day’s filming. I snatch a box of salmon nigiri and am off. Now, though, had come my chance to find out what each of these foods was really doing to my body.

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Other things, such as stress levels, exercising and sleep can all affect our blood glucose reactions, so the research squad built me log everything I did throughout the day on a little phone app.

Most importantly, though, because their initial data had suggested that different individuals reacted differently to foods, I teamed up with another volunteer of the same gender and age – Leila.

For the next week, Leila and I did and feed exactly the same things together – feeing in the same restaurants and carefully weighing our food to ensure that it was as identical as possible. Textbooks used to say our bodies should respond to them in a similar way. The Israeli researchers suspected that we wouldn’t.


Find out more

Trust Me I’m A Doctor is broadcast on BBC Two at 20:00 GMT on Wednesday 27 January – catch up afterwards on BBC iPlayer.


A fortnight later when our results went through I could not have been more flabbergasted. Virtually all my “healthy snacks” such as grapes and sushi caused me big blood sugar spikes, as did a chicken sandwich, and cereal. On the “good” menu, though, was chocolate, ice cream and regular cola.

For Leila, the results were very different. Whereas pasta was “bad” for me, it was fine for her. Yoghurt was good for me, but bad for her, and our responses to bread and butter were also complete opposites.

No-one seems to have suspected this degree of individual difference existed, simply because such a controlled examine on so many people has never been did before. There is, it seems , no such thing as a “high GI” or “low GI” food – it depends entirely on your own body. But why do our bodies vary so much? Well, the team also have a handle on that now too – and it’s an answer that has arousing implications.

Image copyright iStock Image caption Doughnut or vegetables? The healthy selection may not be so simple

Along with our roster of health tests, Leila and I both also devoted the researchers a stool sample. From this, their laboratory was able to discover the composition of our intestine microbes. We all carry thousands of different bacteria, viruses and fungus in our intestines, which not only help break down the food that we feed, but also produce a huge scope of compounds that our bodies absorb and which can influence almost every aspect of our lives, from our immune system, to our metabolism, to our neurotransmitters.

Because of technological breakthroughs in gene sequencing in recent years we began to get to grips with the diversity and importance of these communities that are very much part of “us”.

By comparing the intestine microbes of the hundreds of examine volunteers with their blood sugar reactions, Segal and Elinav have been able discover that our microbes might be the key to why our blood sugar spikes with different foods are so individual. The chemicals they produce, it seems, control our bodies to this extent. What is especially arousing about that fact is that – unlike our gene – we can actually change our microbes. And that is very good news indeed for any of us who find that our favourite foods turn out to be “bad” for our blood sugar levels.

When it comes to my own microbes, at the moment I have a mix of good news and bad. The variety of different types of intestine bacteria I have is limited and that’s not ideal.

Healthier people, it seems, have a wide diversity. However, the ratio between two of the main ones I do have is in the good category. I also observed it interesting that I had a lot of a gut bacterium associated with polycystic ovary condition. It was a huge surprise to me that there could be such a is connected with microbes living in my lower intestine and a condition like that.


What is polycystic ovary disorder?

The three main features of PCOS are:

Cysts that develop in your ovaries( polycystic ovaries) Your ovaries not regularly releasing eggs( ovulating) High levels of “male hormones” called androgens in your body

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