What Is 5-HTP & How Long Does It Take to Work?

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When you eat foods that contain the amino acid tryptophan, your body uses some of it to make 5-hydroxytryptophan, or 5-HTP, a chemical that's also available in supplement form. 5-HTP converts into serotonin, an important neurotransmitter in the brain. Serotonin is partially responsible for controlling your mood and behavior, so increasing serotonin levels may help you lose weight by changing your eating behaviors.

5-HTP for Weight Loss

Taking 5-HTP supplements may help you lose weight by reducing your appetite and cravings for carbs. 5-HTP supplements increase serotonin levels in the brain, and serotonin naturally suppresses your appetite, helping you eat less, explains The Oz Blog. Increasing serotonin levels may also help improve your mood and help you avoid emotional eating due to depression or anxiety.

How Long It Takes

Since the body uses 5-HTP to make serotonin, your serotonin levels will start to increase as soon as you start taking a 5-HTP supplement. It may take several weeks for you to notice the full effects it has on your appetite and eating habits, according to The Oz Blog. Don't take the supplement for more than 12 weeks at a time unless directed to do so by your doctor. Make the most of 5-HTP's appetite-suppressing effects by taking a dose two or three times a day about 30 minutes before a meal. This gives your brain time to process and convert the chemical before you eat.

Evidence for 5-HTP

Researchers have been studying the effects of 5-HTP on appetite since the 1980s with some promising results. A study published in the "Journal of Neural Transmission" in 1989 found that obese women who took 5-HTP for five weeks consumed fewer calories that those who took a placebo. A study published in 1992 in "The American Journal of Clinical Nutrition" found that obese women who took 5-HTP lost weight during two six-week periods -- about 2 percent of their initial body weight during the first period and an additional 3 percent during the second six weeks. During the first period, study participants were not given any dietary restrictions. During the second six weeks, participants were asked to follow a lower-calorie diet with no high-carb foods between meals. Participants who took a placebo did not lose significant weight during either period.


As a dietary supplement, 5-HTP is not approved by the U.S. Food and Drug Administration to treat obesity or any other medical condition. It's important to talk to your doctor before using 5-HTP. Too much serotonin can cause a dangerous condition called serotonin syndrome, so it's important to refrain from taking 5-HTP if you're taking antidepressants or other medications that increase serotonin levels, such as the pain relievers tramadol and meperidine, or migraine medications. Even though some studies on the effects of 5-HTP for weight loss used high doses of the supplement, it's best to start with 50 milligrams one to three times daily, cautions the University of Maryland Medical Center. Talk to your doctor about increasing your dosage if you feel the supplement isn't helping you control your appetite after several weeks.

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