Why are diet pills bad for you? Here’s what Dr. Sally Norton explains.

First and foremost there is no evidence that diet pills actually work.

Think about it for a minute. 

The current obesity crisis is threatening to cripple the NHS due to the costs of treating obesity-related disease. 

If there was a drug that effectively and safely helped people lose weight, do you think the NHS would be keeping it a secret?

Or do you think GPs would be offering it to every one of the 60 per cent or so of us who are currently overweight.

Or at least the 25 per cent who are obese? 

Don't you think the drug companies would be covering every billboard and magazine page with adverts for the 'cure' - they would stand to make a fortune. 

A diet-pill that actually works is the 'holy grail' of medicine that everyone is searching for.

There is currently only one drug that is prescribed specifically for weight-loss in the UK - the other was withdrawn due to the risk of side-effects. 

This drug, orlistat, works by stopping you absorb fat from your intestine, therefore you end up taking in fewer calories. 

What's the downside? 

If you eat fatty food and don't absorb it properly you get unpleasant wind and diarrhoea - and occasionally incontinence - with the net result that many of my patients will simply not take the drug if they fancy a fatty meal. 

So, instead of needing willpower not to over-indulge, you simply need the willpower to make yourself take the drug that will put you off over-indulging. 

Not a great premise for a successful treatment. 

As a result, weight loss with this drug is modest, and is often regained once the drug is stopped.

Add to that the fact that healthy fats - and the vitamins we absorb with them - are good for us in moderation and you will see why I don't prescribe it.

There are a few other drugs being approved in the US that help suppress the appetite, but let's face facts. 

Most of us who are overweight don't just overeat because we are hungry.

It's the other reasons - habits, emotions, an unstoppable urge for chocolate or chips - that lead to the pounds creeping on. 

Reducing our appetite probably won't change that at all.

To help you lose weight, drugs have to do one of two things - alter the way your intestines function or alter the way your brain functions. 

Drugs are not selective enough to target the specific areas of these two organs that are purely responsible for weight gain - we don't really understand what they are anyway.

So, it's no surprise that drugs that help us to lose weight often interfere with other functions of the intestine or brain - possibly in unwelcome ways. 

So drugs that 'boost the metabolism' by raising your pulse rate can put you at risk of heart problems, palpitations, headaches and high blood pressure. 

Drugs that act on the brain by reducing depression or trying to reduce appetite may cause mood swings, sleep disturbance or increase the chance of serious problems like strokes.

At least you know what you are getting if you have a prescribed drug, as the possible side-effects and risks are listed ad infinitum. 

But buying diet-pills on  the internet means you have no idea what they really contain and whether they could interact with drugs you may already be taking...or make an existing health problem worse. 

We recently heard the sad story of Eloise Parry who died after taking dinitrophenol, or DNP. 

DNP is a toxic chemical declared unfit for human consumption by the Food Standards Agency. 

Ingesting this poison can lead to nausea, vomiting, restlessness, flushed skin, sweating, dizziness, headaches, rapid respiration and irregular heart-beat, possibly leading to coma and death. 

Despite this, it appears that these drugs are being made in clandestine laboratories before being marketed to vulnerable people, desperate for that miracle solution to their - often largely imaginary - weight problem.

So, don't play with your health. 

Yes, being overweight may be a risk - but don't swap that risk for a diet-pill that may be a lot worse for you and probably doesn't work anyway.

And, as soon as that miracle diet-pill, that actually leads to safe and significant weight-loss, becomes available, you will be the first to know.