20/05/2012 18:27 BST | Updated 20/07/2012 06:12 BST

Dieting for Two - Think Twice About the Latest Advice on Dieting While You're Pregnant

Last week pregnant women have been told to stop eating for two, put down their forks and go on a diet instead. Limiting calorie intake, the reports say, will not harm unborn babies. Added to this advice was the extra push pregnant women need to feel guilty enough to feel forced into dieting: "Following a controlled diet has the potential to reduce the risk of a number of pregnancy complications." Together with the reassurance: "Dieting is safe and that the baby's weight isn't affected."

Released at the same time, however, were results of another study that suggested babies of mothers who diet in early pregnancy may have an increased risk of obesity and type 2 diabetes throughout their lives.

2012-05-19-2435076479_9667e97f9a.jpg The second study wasn't widely reported but the first study encouraging pregnant women to diet was all over the news, despite advice from the National Institute for Health and Clinical Excellence (NICE), published in 2010, saying: "Dieting during pregnancy is not recommended as it may harm the health of the unborn child." Also despite it being understood that dieting increases levels of the stress hormone cortisol, which causes weight gain, and which also can have an effect on an unborn baby.

If you're thinking about dieting (whether you're pregnant or not), consider this: overeating is a compulsion and it is driven primarily by dieting. Any attempts at trying to eat less will result in you eating more. This is a built-in survival reaction and it's caused by many chemical, psychological and biological processes, including changes in the hormones related to hunger and satiety. Dieting makes you feel hungry all the time.

Dieting takes away your choices about what you eat or don't eat. You are driven to eat on automatic. Many dieters are very familiar with this feeling - you decide to cut down, someone offers you a cake, you try not to eat it and then you go into a 'trance' and then find you've eaten it and you regret it, thinking: "Why did I eat that?"

Learning how to stop dieting switches off this reaction and leaves you free to choose whether to eat the cake or not.

This is the same for pregnant women, of course. Dieting while pregnant will mean you're ultimately up against survival and biological drives that can override conscious decision making. Trying to 'hold off' eating in the long term is a bit like trying to hold your breath. Hold your breath and you can do it for a while but eventually you'll have to take in a massive gulp of air to compensate for the deficit. Breathing, which is essential for your survival, is a reflex and you can't control it for more than a few moments. Like with all survival essentials, it's controlled automatically by your brain. Eating is also a survival essential and while it's not as urgent a need as breathing and so not a reflex, it's still largely controlled by your brain. If you cut down on food, this will mean eventually you'll have to eat more to compensate for the defecit.

There is a complex motivational balance that can override this process (involved in eating disorders such as anorexia), but for most people, trying to diet will result in eating more.

So why are pregnant women being advised to diet?

What I'd like to know is who funded this study? It was the National Institute For Health Research (NIHR), but who funds them? The NIHR website says it's "collaborative and multi-centred research in the public interest in partnership with and for industry." The NIHR has close links with the pharmaceuticals weight-loss industry. Given what we know about conflict between industry profits and public interest, can studies linked to big corporations dependent on profit ever be primarily in the interest of the public? History shows that in this situation the public usually loses out and profits come before public health. Look at the tobacco industry:

Confronted by compelling peer-reviewed scientific evidence of the harms of smoking, the tobacco industry, beginning in the 1950s, used sophisticated public relations approaches to undermine and distort the emerging science.

A number of industries have subsequently followed this approach to disrupting normative science. Claims of scientific uncertainty and lack of proof also lead to the assertion of individual responsibility for industrially produced health risks.

From a study by Allan M. Brandt PhD, Department of the History of Science and the Department of Global Health and Social Medicine, Harvard University

The pharmaceutical side of the weight loss industry is known to be spreading anxiety about weight, as it knows the more weight anxiety there is, the more weight problems there will be and in increasing the problem they increase their consumer base ready for when they produce the 'miracle' weight loss drug they're currently working on.

With the knowledge we now have about the real effects of dieting, we really need our media to start asking questions like: Why did this study hit the headlines but the study advising against pregnant women dieting did not? Will someone profit from advising pregnant woment to diet even though it's well known that dieting will increase a woman's biological drive towards compulsive eating as well as her cortisol levels (meaning she is likely to gain weight and not lose it, affecting the baby and increasing the chance of complications) and when other studies show dieting when pregnant has a chance of producing babies at risk of obesity and diabetes?

Ideally, we need to ask these questions before reporting studies that advise dieting, especially to pregnant women.

Image © Erik Langner