Caffeine is a natural, plant-based alkaloid that comes from sources like coffee beans, cacao pods, tea leaves, cola nuts and guarana berries. This substance is consumed in chocolate and caffeinated drinks and added to pain-killing drugs. Because it is a chemical, caffeine has some physical effects on the human body, although it does not directly suppress your appetite.
Caffeine has only a minor, brief appetite-suppressing effect, according to Mayo Clinic nutritionist Katherine Zeratsky. The chemical also increases the level of fatty acids circulating in your body. This effect enhances fat oxidation, although the effect is less pronounced in people who consume caffeine regularly. Caffeine reduces fatigue and gives you more energy, which helps you feel good while dieting and gives you a boost if you are on an exercise program. You may temporarily lose some water weight after taking caffeine because it has diuretic effects that make you urinate more frequently, but the loss is temporary.
Caffeine stimulates your central nervous system, raises your heart rate and relaxes your air passages, which lets you breathe more freely. The drug's effects are usually harmless, but overconsumption of caffeine can cause anxiety, high blood pressure, nausea and insomnia, Zeratsky advises.
Caffeine's physical effects happen very quickly because the chemical is rapidly absorbed by the body. Caffeine is taken into the bloodstream through the stomach and small intestine, and it enters your system within 15 minutes of drinking coffee or taking it in through another beverage, food or pill, Everydiet advises. The body completely absorbs caffeine within 45 minutes.
Some diet pills contain caffeine as an active ingredient because of its perceived appetite-suppressant qualities. The amount in pills is usually equal to about two to three cups of regular brewed coffee, according to Erin Richards of the Science 2.0 website. That amount is not harmful for most people, but it can cause problems when combined with dietary caffeine intake from chocolate, soft drinks, coffee and tea. Too much caffeine leads to headaches, nausea, tremors and gastrointestinal problems. Abruptly stopping caffeine intake after regularly ingesting it causes withdrawal symptoms.
Healthy weight-loss strategies are more effective in the long run than relying on chemical appetite suppressants. Make goals and commit to them, add more healthy foods like whole grains, fruits and vegetables to your diet and exercise every day for at least half an hour. You can continue to consume caffeine during your weight-loss program, but beware of adding calories by adding sugar and cream to coffee or tea or drinking high-calorie soft drinks and eating chocolate candy.
- Everydiet: Coffee (Caffeine) and its Effects in the Human Body
- Mayo Clinic; Does Caffeine Help With Weight Loss?; Katherine Zeratsky; May 2011
- Science 2.0; The Real Deal Behind Diet Pills; Erin Richards; November 2008
- Medline Plus: Caffeine
- Mayo Clinic; Weight Loss, 6 Strategies for Success; December 2010