Q & A Thursday: the many factors that contribute to obesity

Posted by kathryn in Q & A Thursday

Next on Q & A Thursday Andrew has asked a big, big question. He directed me to this podcast, featuring Barry Glassner, author of The Gospel of Food and then asked:

I was specifically interested in the role stress, economic and social environment has regarding body fat and diets. Do you further understand Barry’s idea’s and can you write about these points a bit more?

The solution for obesity often gets reduced down to a simple message – people need to eat less and move more. Blame for the rise in obesity has been spread around – it’s the food manufacturers fault, it’s our lifestyles, our parents, our genes and on it goes.

While all of this is true and, for most people, moving more and eating less will lead to weight loss, it’s not quite the full story. Despite the simple messages (and I’m as guilty of that as the next nutritionist), obesity is an immensely complex problem and there’s still a whole lot of stuff about it we just don’t understand.

For example, we don’t fully understand how appetite works. We know there are hormones involved, like leptin and ghrellin, but how they interact to make us feel hungry and also satisfied, is uncertain. There’s also a lot we don’t understand about metabolism and these are two crucial factors to understanding obesity.

What is certainly true is that obesity is a multi-factorial condition. Along with the food we eat, and the exercise we do, stress, economics and social environment all play a role in obesity. It’s a large and complex topic. To try and do justice to it, I’m going to split my answer. This post is about the effects of stress on obesity and I’ll cover economics and social environment in later posts – probably early next week.

What is stress?

We’ve all experienced stress, we’ve all talked about “being stressed” and it’s something that affects people of all ages and all walks of life. Some stress can be a good thing, however excessive and long-term stress can have disastrous consequences for our health. It’s this chronic kind of stress that plays a role in obesity.

When stressed you may feel your heart beating, be aware of sweaty palms and even shallow breathing. However, in your body, changes that you’re unaware of, are also occurring. Stress is a hormonal reaction. It’s kicked along by adrenaline and nor-adrenaline, which then go on to have an effect on many other body systems. Your immune functioning is reduced, your digestion is affected and stress also changes blood glucose and fatty acid levels.

How stress changes the way we eat

Stress contributes to obesity in a number of different ways. From a purely practical sense, when stressed you probably concentrate less on the foods you’re eating eat. There’s less time for shopping and you’re more likely to grab food on the go, or get take-away in the evening, rather than cooking a home-cooked meal. This style of eating tends to be higher in fat and kilojoules.

The hormonal effects of stress.

While it is true that people might eat a higher kilojoule diet when stressed, there are indications that the resultant weight gain can be out of proportion to what was eaten. A number of studies have shown that stressed rats gain more body fat than unstressed rats and this weight gain is in excess of their kilojoule intake.

It is believed that neurotransmitters released under stress can actually stimulate the body’s fat cells to grow in both size and number.

There is also some evidence that the urge to eat “comfort foods”, when stressed, may be part of the hormonal response to stress. Changes in eating patterns may not simply be because of lack of time and focus, there may be biological drivers at work.

This post is part of Q & A Thursday – a weekly burst of blogging, where you get to dictate the subject matter. Q & A Thursday is all about simple, practical and sensible answers to food, diet and health dilemmas sent in by readers. If you have a question you’d like answered, then either leave a comment or send me an email.

16 August, 2007