Can Popping Pills Really Help you Lose Weight?

By Dietitian Juliette Kellow BSc RD

Want to lose weight quickly for your holiday, need help to shift a couple of stubborn pounds or always find it difficult to get started on a diet?

Then take a trip to your local health store or surf the internet and you’ll find a huge number of slimming pills that promise the ultimate quick fix.

From fat-blockers and metabolism-boosters to pills that prevent hunger and beat cravings, there’s something for everyone – and more often than not, the promise that we can get maximum results with minimum effort is simply too good to resist!

Do Slimming Pills Work?

But do slimming pills really work? Currently in the UK, there is only one anti-obesity drug available on prescription – Xenical (Orlistat). Reductil (Sibutramine) used to be available but has been withdrawn. Orlistat is also now available over the counter in the form of Alli Weight Loss Pills. These two drugs work in completely different ways.

Xenical blocks the action of lipase, the enzyme that digests fat in the intestine and stops around 30 percent of the fat you’ve eaten from being absorbed.

As a result, your body loses around a third of the calories provided by this fat so you start to lose weight!

In contrast, Reductil enhances satiety by indirectly boosting levels of serotonin, a chemical that helps you feel full. This means you feel more satisfied with less food and so eat smaller amounts and lose weight.

Slimming Pills Clinincally Proven to Work

The good news is that, unlike many of the slimming pills you can buy at your local health store, Xenical is clinically proven to help people lose weight and generally receives the support of most health professionals.

Carey Halls, information pharmacist at the National Pharmaceutical Association believes there’s a very good case for using prescribable drugs with people who are obese and meet certain medical criteria.

She says, ‘Many clinical trials have looked at the efficacy of Xenical in the treatment of obesity and found it to successfully help obese people lose weight.’

But like many health professionals, Carey believes the success in treating obesity isn’t just the result of the active ingredients, but is also due to the lifestyle advice that patients receive. ‘People who are prescribed Xenical are closely monitored by their doctor. They receive diet and exercise advice and get plenty of support to help them along the way,’ Carey explains.


Unfortunately, it’s a far cry from the types of slimming pill you can buy over-the-counter in chemists or health stores. In general, there’s little evidence that the ingredients they contain will work to help you lose weight.

‘There’s not much research to suggest that over-the-counter slimming pills induce weight loss,’ says Carey. ‘Even if research has been carried out, it’s usually only one or two small studies, the results of which haven’t been repeated or seen in larger studies.’

Many over-the-counter slimming tablets also provide very little information on the packaging, often even failing to provide basic facts on how the product supposedly works to aid weight loss.

Carey explains, ‘Many of these products are not licensed medicines. This means they’re not allowed to make certain claims such as “speeds up metabolism” or “stops fat from being absorbed”. This in turn means there’s often a worrying lack of information on the packaging.’

Side Effects of Over the Counter Slimming Pills

But the problems with over-the-counter slimming pills don’t just stop there. Carey believes some may actually do more harm than good.

‘Certain over-the-counter slimming pills may not be suitable if you have medical conditions such as diabetes or high blood pressure, yet this may not be clear from the packaging with the result that women with these conditions still try them. Some may also interact with other medications. For example, taking a slimming pill that includes a thyroid-stimulating ingredient could interfere with prescribed medication for an underactive thyroid, potentially causing problems. Again the packaging might not make this obvious.’

But unfortunately, a lack of information, little proof they’ll work and potentially putting your health at risk is not the only price you’ll need to be prepared to pay.

Most over-the-counter pills are extremely expensive, too, with the result that you can be sure you’ll lose pounds – but probably not the right sort!

Choose Carefully

Nevertheless, if you’re still tempted to try an over-the-counter slimming tablet, there are plenty to choose from. Bear in mind that most of them recommend, or come with, a reduced-calorie diet plan and suggest taking more exercise, which generally explains why they result in weight loss!

While some of these tablets may claim to be supported by research, this is likely to be a ‘one-off’ small study. Such as that for capsiplex which concentrated on just 25 subjects. See our A-Z of popular slimming tablets for some examples.

Juliette’s Verdict

There’s certainly a place for Xenical in the treatment of obesity. If you think you might be a suitable candidate to try this drugs, see your GP for advice or pop to your local pharmacy and ask about Alli Weight Loss Pills.

However, there’s little scientific evidence to suggest that over-the-counter slimming pills will help you lose weight and keep it off.

You wouldn’t expect vitamin supplements to compensate for a diet that contained no fruit or veg, and you shouldn’t expect an over-the-counter slimming pill to compensate for a high-calorie diet and inactive lifestyle!

Lose Weight Safely and Sensibly

To lose weight safely and sensibly, you need to tackle the poor eating habits and lack of exercise that helped you gain weight in the first place. If you concentrate on making long-term changes to your diet and lifestyle, you won’t need to resort to quick fix remedies.

But if you still can’t resist the fantastic promises, at least avoid those products that make outrageous claims. If a product sounds to be good to be true, then it probably is!

Avoid Slimming Pills if They…

  • Promise a quick fix – sorry, but you didn’t put the weight on overnight so you can’t expect to lose it overnight!
  • Promote rapid weight loss – that’s anything more than 2lb a week!
  • Suggest you don’t need to change your eating habits or take more exercise – you know it’s not true!
  • Fail to come with dietary advice – or worst still, come with a faddy diet that cuts out certain groups of foods, considerably restricts your food intake or encourages you to eat vast amounts of one particular food!

Do Slimming Pills Ever Work?

Sometimes over-the-counter slimming pills can work, but this generally has little to do with their ingredients. They’re more likely to help you lose weight because…

  • They come with a reduced-calorie diet plan that generally provides between 1,000 and 1,400 calories a day and recommend taking more exercise. It’s this that causes the weight to drop off!
  • You usually need to drink large amounts of water with the pills. This helps to fill you up so you feel less hungry and eat less as a result!
  • You’ve spent a lot of money on something you hope will help you lose weight so without even realising it, you make changes to your lifestyle such as eating less or exercising more!

Try the Food Diary and tools in Weight Loss Resources free, for 24 hours


References and Sources:

JAMA - Weight control and risk factor reduction in obese subjects treated for 2 years with Orlistat

Medicines and Healthcare Regulatory Agency UK - Public Assesment Report - Orlistat

International Journal of Obesity Related Metabolic Disorders - Sibutramine: A novel anti obesity drug


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Using the food diary and tools in WLR can help you lose weight without pills, and can provide the low calorie, low fat diet that most slimming pill manufacturers recommend. We'd advise keeping a food diary for a couple of weeks before making a decision about pills - many people find that just making a few, relatively minor, changes to their eating habits sets them on the path to sustainable weight loss. You can use the WLR food diary Free for 24 hours.

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