Weight loss pills explained


Losing weight is tough when life is so busy. It’s time-consuming to cook healthy meals and exercise every day, and buying lots of fresh fruits and vegetables can be very expensive. Even with the best motivation, it’s difficult to know where to start and what to do when you want to change your lifestyle habits and become a healthier you.

No wonder there’s a million and one products out there promising to take away the stress, time and expense of losing weight. Wouldn’t it be so much better if it were as simple as just popping a pill?

Diet pills are often marketed as quick and easy ways to melt the fat away. But do their claims match up with the evidence? Let’s take a look.

How do weight loss pills work?

Most weight loss pills are designed to either suppress your appetite or lower your body’s ability to absorb fat from food. Some are prescription-only, while others are easily available over the counter or in health food stores. Different regulations and standards apply depending on whether or not the diet pill is prescription-only.

What’s in weight loss pills?

Generally, diet pills contain a variety of vitamins and herbs, sometimes accompanied by stimulants. Consumer advocacy group CHOICE has looked at the most common ‘active ingredients’ in weight loss pills in Australia. Here’s a summary of the findings:

  • Hydroxycitric acid (HCA), aka brindleberry, Malabar tamarind, or Garcinia quaesita: Producers claim it boosts your metabolism, reduces appetite and even limits body fat production. The evidence surrounding this claim appears to be mixed, with some showing improvement while others show no difference.
  • Bitter orange: It’s marketed as a ‘fat burner’ which increases your metabolism and decreases appetite, but again the evidence appears to be mixed. Some studies seem to suggest a risk of cardiovascular side-effects, particularly for those with heart conditions or taking other medications.
  • Capsicum annum: This is claimed to increase the metabolic rate and reduce appetite, with mixed proof of this. Some studies have shown that eating spicy food can help you eat less. A possible side effect is burning pain. Maybe a bit too spicy!
  • Green coffee extract: The claim is that this ingredient increases metabolism and glucose control. While there are no known side-effects, there haven’t been significant studies.
  • Green tea extract: Again, there is more conflicting evidence on this one, with some studies showing efficacy when taken with caffeine. It’s claimed to reduce body fat production and increase your metabolism.
  • Chitosan (produced from the powdered shells of crustaceans): Producers say it binds to dietary fat and stops absorption. Study results vary, with none showing significant weight loss outcomes. If it does work, it may affect the absorption of nutrients by binding to them as well.
  • Chromium picolinate: This is claimed to raise insulin sensitivity (i.e. reduce the amount of insulin you need to produce muscle and fat cells to absorb glucose). According to the National Institute of Health in the US, high insulin sensitivity is generally good because its opposite, insulin resistance, is a precursor to diabetes.

How are diet pills different to weight loss shakes?

While weight loss shakes are designed to replace meals to help you reduce food intake, diet pills are not a meal replacement. Instead they are meant to reduce your appetite and increase your metabolism.

Depending on the product, you take these pills at particular times during the day to limit how much you eat or how often you snack, or to limit how much fat your body absorbs from your food. This means that, to get results, a bit more planning is involved than with shakes which you just drink instead of your usual meal.

How do weight loss shakes work?

Things to be aware of

Manufacturers of weight loss products often use testimonials to try to convince you that they can melt your fat away. It’s important to take testimonials with a grain of salt. In 2005, the law changed so that product testimonials and images must show ‘typical cases’ but what that means is not well defined. One way to check the validity of these cases is to read the fine print, where they may explain the results shown were also produced through significant changes in diet and exercise habits.

The meaning of complicated-sounding technical terms used in marketing weight loss pills and other products isn’t always clear to those of us who don’t have science degrees. For example, ‘clinically proven’ sounds more impressive than it might really be. One study may show that a product works, but when it comes to science, it’s generally necessary for the same results to be produced by multiple studies run by different people before something is accepted as fact.

Comparisons are another popular advertising tool. Read the fine print to find out exactly what they’re comparing their results to. Maybe a claim about losing 5% more weight when using a certain pill is compared to doing nothing at all, for example.

Are weight loss pills safe?

It’s important to remember that while they look like medicine and they might be marketed like medicine, over-the-counter diet pills are not regulated in the same way as prescription medicines. The Therapeutic Goods Administration (TGA) – Australia’s regulatory body for medical products – requires a lower standard of testing for over-the-counter products which contain active ingredients that are already approved substances.

This also means that there is a lower standard of proof of efficacy than prescription medicines. That being said, the TGA does require reasonable proof to be provided upon registration, and does randomly audit products to verify the provided documentation. The TGA recently banned some weight loss products on the basis of risk review, or in one case, the discovery that the product contained a banned substance.

Stimulants (like caffeine) can cause heart palpitations in certain doses, so bear this in mind if you’re sensitive to stimulants, have cardiovascular health issues, or already drink quite a lot of coffee. Some products designed to prevent the absorption of fat may also impact on your ability to absorb nutrients, depending on how they work. If you have health problems, or are taking other medication, it’s important to talk to your doctor to avoid products which may adversely affect your health.

Do weight loss pills work?

Like any weight loss supplement, non-prescription diet pills are unlikely to do much without a healthy controlled diet and regular exercise. We know this sounds like a broken record – diet and exercise, diet and exercise – but that’s because it’s the best way to lose weight effectively and sustainably in the long term. What these pills can do is enhance the effects of your own hard work in changing your lifestyle habits.

Prescription weight loss products are generally much better studied. Studies have shown that in conjunction with healthier lifestyle changes, these pills can assist weight loss. But they’re still far from that magic bullet solution.

It’s a good idea to talk to your doctor about the products you have in mind and your particular needs. They will be able to help you find safe tools to supplement a healthy diet and exercise plan. The takeaway from all of this is that diet pills are best treated as a supplementary tool, rather than a magic pill that will melt the kilos away.

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