Due to its customary use in African cuisine and folk reputation StrictionD Review as a health food, a research group from Cameroon (Western Africa) set up a randomized double blind study in 2005 to see if Irvingia gabonensis could help with weight loss. 40 obese subjects were divided into placebo and experimental groups. The experimental group received 1.05 grams of Irvingia seed extract 3 times a day (total 3.15 grams) for 30 days.
Subjects were examined weekly and tested for body weight, body fat and hip/waist circumferences. Blood pressure was measured and blood samples were also collected after an overnight fast and tested for total cholesterol, triacylglycerol, HDL-cholesterol and glucose. The subjects were interviewed about their physical activity and food intake during the trial and were instructed to follow a low fat diet of 1800 calories per day and keep a food record for seven days. At the end of the 30 day trial, the Irvingia group had lost an average of 5.26 kilos (11.5 lbs) and the placebo group had lost only 1.32 kilos (2.9 lbs). The group receiving Irvingia also experienced a decrease in systolic blood pressure, total cholesterol, triglycerides and LDL cholesterol. HDL cholesterol increased.
This was the first study that suggested a weight loss benefit from Irvingia. Why did the Irvingia group lose more weight? It's not clear, but in studies of free-living subjects, increased weight loss often means that the experimental group ate less, not necessarily from a direct action on metabolism, hormones or physiology. In March 2008, the same research group published the results of their second study about Irvingia and weight loss. This time, Irvingia was combined with Cissus quadrangularis, a succulent vine native to West Africa and Southeast Asia. 72 subjects were divided into three groups, placebo, Cissus extract only (150 mg 2X/day) and Cissus-Irvingia combination (250 mg combined Cissus-Irvingia 2X/day).
All the same tests and measurements were taken as in the 2005 study. After 10 weeks, improvements were seen in total cholesterol, LDL cholesterol and fasting blood glucose. The placebo group lost 2.1 kg (4.6 lbs), the cissus group lost 8.82 kg (19.4 lbs) and the Cissus-Irvingia group lost 11.86 kg (26.1 lbs). Attributing 26 pounds lost in 10 weeks solely to a fiber supplement is highly unlikely if not impossible, so the researchers (Oben and Ngondi) thought there was something else going on. They proposed that PPAR gamma, leptin, adiponectin or glycerol-3 phosphate dehydrogenase could all be potential mechanisms through which Irvingia gabonensis might affect body weight in overweight humans.