With around 41% of Australian males and 25% of females now classed as overweight, it is easy to see how diet pills have become a thriving multi-billion dollar industry world wide.1 In theory, diet pills can offer a comfortable and timely alternative for weight loss without the restrictions of many traditional approaches.
Though many sites promote diet pills as having dramatic effects on weight loss most do not have significant scientific studies backing their claims, nor do they properly disclose likely side affects. According to the executive director of the Australian Society for the Study of Obesity, Dr Tim Gill, studies have shown that the overall benefit of diet pills can be described "at the very best...minimal". Research has shown that early results for diet pills are often promising, however this can largely be attributed to people initially following the restrictive diet and exercise instructions associated with the diet pill.
How do diet pills work?
There are 3 ways diet pills can operate:
- Appetite suppression
- Increased metabolism
- Reduction or body's ability to absorb specific nutrients in food, namely fats
Types of diet pills
Non-prescription diet pills
The non-prescription diet pills usually contain caffeine or another natural stimulant that will increase heart rate and basal metabolic rate. This can also serve to burn more energy during workouts and can be quite effective in weight loss. A common extract is green tea, which seems to increase metabolism and slow fat production. Also citrus fruit extracts are often coupled with caffeine to reportedly increase energy while boosting metabolism.
Prescription diet pills
Prescription diet pills are often more effective, however require medical supervision as a result of potential side effects.
Appetite suppressant diet pills such as phentermine (Adipex-P, Fastin), sibutramin (Meridia) and diethylpropion (Tenuate) work by blocking the reuptake of chemicals such as serotonin and norepinephrine to the brain. These chemicals are responsible for satiety levels and by having more of these chemicals floating around, the brain thinks the body is full.
Fat blocking diet pills (Xenical) work by inhibiting the action lipase enzymes. These enzymes normally break down fat as it reaches the intestinal tract. As such, with a lipase inhibitor there is a portion of the fat ingested that gets passed through the body instead of being absorbed.
There has also been evidence to suggest that other drugs, such as antidepressants (Prozac, Topomax), used off label as a diet pill have assisted weight loss. However the direct cause of weight loss is poorly understood and it is important to use these and all diet pills wisely and under the supervision of a doctor.
Diet pill side effects
Many of the prescription diet pills have demonstrated unpleasant side effects. The fat blocking diet pills can cause nausea, stomach aches and diarrhea. Conversely appetite suppressant diet pills stimulate the sympathetic nervous system, potentially causing elevated heart rate and blood pressure. People who already suffer from heart disease, irregular heartbeat or high blood pressure can have an increased chance of heart attack and cardiac arrest.
Diet pill success
Diet pills are usually only effective for short time periods, up to 6 months, as your body tends to develop a tolerance to the drug. Some diet pills can assist weight loss of up to 10kg or 10% of body mass, however tend to become ineffective after this point. Once diet pills are stopped if a healthy eating and exercise routine are not followed, the lost weight will come back just a quickly as it was lost. In some instances diet pills can work, however to maintain long term weight loss there is no substitute for a healthy diet and regular exercise. Below are some ways to naturally increase your metabolism:
- Eating breakfast
- Eating in smaller portions
- Strength training
- Interval training
- Spicy foods
1. Australian Bureau of Statistics. National Health Survey 2004-05: Summary of results. ABS cat.no. 4364.0. Canberra:ABSEmotional Eating, Weight Loss