Amount many different weight loss solutions ,plant extracts have stand out for their effectiveness and safety .They tend to work via one or more of these mechanisms:
Reduce appetite, making you feel more full so that you eat fewer calories.
Reduce absorption of nutrients like fat, making you take in fewer calories.
Increase fat burning, making you burn more calories.
Caffeine is the most commonly consumed psychoactive substance in the world .It is found naturally in coffee, green tea and dark chocolate, and added to many processed foods and beverages.Caffeine is a well known metabolism booster, and is often added to commercial weight loss supplements.
How it works: Short-term studies have shown that caffeine can boost metabolism by 3-11%, and increase fat burning by up to 29% .
Effectiveness: There are also some studies showing that caffeine can cause modest weight loss in humans .
Side effects: In some people, high amounts of caffeine can cause anxiety, insomnia, jitteriness, irritability, nausea, diarrhea and other symptoms. Caffeine is also addictive and can reduce the quality of your sleep.
There really is no need to take a supplement or a pill with caffeine in it, the best sources are quality coffee and green tea, which also have antioxidants and other health benefits.
Green Tea Extract
Green tea extract is a popular ingredient in many weight loss supplements.This is because numerous studies have shown the main antioxidant in it, EGCG, to aid fat burning.
How it works: Green tea extract is believed to increase the activity of norepinephrine, a hormone that helps you burn fat .
Effectiveness: Many human studies have shown that green tea extract can increase fat burning and cause fat loss, especially in the belly area.
Side effects: Green tea extract is generally well tolerated. It does contain some caffeine, and may cause symptoms in people who are caffeine sensitive.
Bottom Line: Green tea and green tea extract can increase fat burning slightly, and may help you lose belly fat.
Green Coffee Bean Extract
Green coffee beans are simply normal coffee beans that haven’t been roasted.They contain two substances believed to help with weight loss, caffeine and chlorogenic acid.
How it works: Caffeine can increase fat burning, and chlorogenic acid can slow the breakdown of carbohydrates in the gut.
Effectiveness: Several human studies have shown that green coffee bean extract can help people lose weight .
A review of 3 studies found that the supplement made people lose 5.4 more pounds (2.5 kg) than placebo, a dummy pill .
Other benefits: Green coffee bean extract may help lower blood sugar levels, and reduce blood pressure. It is also high in antioxidants.
Side effects: It can cause the same side effects as caffeine. The chlorogenic acid in it may also cause diarrhea, and some people may be allergic to green coffee beans.
Garcinia Cambogia Extract
Garcinia cambogia became popular worldwide after being featured on the Dr. Oz show in 2012.It is a small, green fruit, shaped like a pumpkin.The skin of the fruit contains hydroxycitric acid (HCA). This is the active ingredient in garcinia cambogia extract, which is marketed as a diet pill.
How it works: Animal studies show that it can inhibit a fat-producing enzyme in the body and increase levels of serotonin, potentially helping to reduce cravings.
Effectiveness: One study with 130 people compared garcinia against a dummy pill. There was no difference in weight or body fat percentage between groups .
A 2011 review that looked at 12 studies on garcinia cambogia found that, on average, it caused weight loss of about 2 pounds (0.88 kg) over several weeks .
Side effects: There are no reports of serious side effects, but some reports of mild digestive problems
Raspberry ketone is a substance found in raspberries, which is responsible for their distinct smell.A synthetic version of raspberry ketones is sold as a weight loss supplement.
How it works: In isolated fat cells from rats, raspberry ketones increase breakdown of fat and increase levels of a hormone called adiponectin, believed to be related to weight loss .
Effectiveness: There is not a single study on raspberry ketones in humans, but one rat study using massive doses showed that they reduced weight gain .
Side effects: They may cause your burps to smell like raspberries.
-- Kris Gunnars, BSc, “12 Popular Weight Loss Pills and Supplements Reviewed”Authority Nutrition