Weight loss pills: Do they really work?

March 1, 2014 at 11:46 PM

In this article we shall have a look at some most popular weight loss pills. You will learn how these pills actually act and find out whether they really work or not.

What are weight loss pills?

Weight loss pills, also known as anti obesity medications, are drugs that are meant to control and reduce weight. These agents alter body processes in such a way that it results in loss of body weight. Till now only one drug - Orlistat - is approved by the FDA for long term use.

Most of these drugs are associated with serious complications and side effects. So, under clinical conditions, these drugs are prescribed only when:

  • Obesity posses threat to life or can lead to some potentially fatal complications.
  • Weight loss is not possible by change in life style, dietary changes and physical activities.
  • The choice of these pills is made only when doctors are sure that the benefits of weight loss program through pills outweigh the side effects.

The purpose of this article is to evaluate the truth behind big claims of these pills, their safety and most importantly this article is focused on answering one question that everyone would ask “Do these pills really work?” Read on to unveil the truth behind fat loss pills.

How do these pills act?

Current and potential weight loss pills would act by one of the following mechanisms:

  • Weight gain begins when people starts eating more than their caloric requirements. When this happens, body is left with no other choice but to convert all these extra calories into fat. So, the basic problem is uncontrolled appetite. Most of the weight loss pills basically try to suppress appetite. This goal is achieved by increasing the amount of certain hormones (mainly catecholamine and serotonins) inside body. Studies conducted in animal models have shown that increased amount of catecholamine is linked with decreased intake of protein. Moreover, activation of canabinoid receptors (receptors decreasing the activity of gut and acting on brain to decrease appetite) would be the target for future weight loss pills.
  • Body metabolism is meant for burning calories that you eat. This way the energy of food we eat is transformed into energy available for use. Even when we’re doing any physical activity the consumption of energy continues and this consumption of energy is called basal metabolic rate (BMR). Some people have a higher BMR as compared to others. That explains why some people never get fat no matter how much they eat. Some weight loss pills function to boost the activity of body metabolic rate. In nut shell, these pills are meant to increase the expenditure of energy. When there is an increase in the expenditure of energy, body calls upon its stored fats to fulfill body’s increasing demands of energy. This is how weight loss occurs.
  • Whatever we eat is absorbed through gut. For instance, the fat present in our diet is absorbed through gut and is sent into the store houses of our body. This stored fat is used in times of need. Overtime this fat keeps on accumulating and result is increase in weight. If we could decrease the absorption of dietary fats and cholesterols, we can actually prevent building up of body fat and weight gain in first place. This what some drugs do. For instance, Orlistat is meant to decrease the absorption of fat and cholesterol. This is how these drugs nip the evil in its bud.

What are some famous weight loss pills?

Here are some famous pills that are used for weight loss purpose:


Once the food gets entry into the small intestine, it gets mixed with pancreatic juice containing several enzymes including pancreatic lipase. Fats present in food are too large to be absorbed as such from gut. That’s why lipase from pancreas first breaks down this fat into its constituents that are afterwards absorbed. These constituents, after their absorption, fuse again to form fat. Orlistat function to inhibit the action of pancreatic lipase. This way fat is not absorbed in first place. It is the only weight loss pill recommended by FDA. This pill, like any other drug, is associated with some side effects like gut upset and foul smelling stool containing high level of fat in it. This condition is called steatorrhea.


This drug was previously a famous drug used for weight loss purpose. It achieves its goal by decreasing appetite. However due to significant health risks, it has now been withdrawn from market in most of countries. The side effects of this drug include headache, insomnia, high blood pressure, dry mouth and increased risks for myocardial infarction.


This is another anti obesity drug that is being tested. It is also prescribed as a weight loss pill in some countries. This drug causes release of certain chemicals (serotonin) in brain that decreases appetite and carving for food. The potential side effects of this drug include nausea, headache, dizziness and excessive loss of appetite.

Alternative weight loss pills

Some alternative medicines include:

  • Conjugated linoleic acid: This is a possibly effective alternative way to lose body weight. It causes side effects like nausea, diarrhea and stomach upset.
  • Green tea extracts: It is believed that green extracts boost metabolism and cause oxidation of fat. But scientific evidence to validate the authenticity of this fact is still not that strong. Potential side effects include nausea, agitation, anorexia and insomnia.
  • ECA stack: It is an alternative method effective in boosting metabolism in humans. This way, this drug actually helps to lose weight. Possible side effects include skin reactions, nausea, hyperthermia, itchy scalp, heart attack, stroke and death.

Final verdict: Are these pills effective?

Well, the total number of drugs that have actually shown to positively reduce weight is very limited. Most of the pills are just false advertisement with no scientific data backing their efficacy in causing weight loss. Some drugs do cause decrease in body weight but there are limitations here too. The results are either too modest or are associated with serious side effects. So, it would be appropriate to say that instead of wasting time and money on weight loss pills, you should actually try those methods that actually work: like weight loss exercises and controlling your dietary patterns.

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Written by: Michal Vilímovský (EN)
Education: Physician
Published: March 1, 2014 at 11:46 PM
Next scheduled update: March 1, 2016 at 11:46 PM
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