Grapefruit for weight loss ?
January 5, 2014 Admin 2
The citrus fruit Grapefruit contains a number of nutrients that have been documented as having the potential to aid in weight loss. The concentrations of these nutrients (in particular, flavanones) in grapefruit juice can vary depending on preparation and country of origin. One such nutrient, Naringenin in particular has drawn interest in recent years because of its activity as an insulin sensitiser, particularly when considered a counter to such conditions as high fructose induced models of insulin resistance.
This is not the first time that grapefruit has been considered an aid to either a metabolic disorder or used in relation to weight loss. In the 1930′s The so called ‘grapefruit diet’ was reported to aid weight loss by the action of special fat burning enzymes present in grapefruit itself.
The diet gained popularity once again in the 1970′s where it was altered somewhat from its original low carbohydrate roots and re-engineered to recommend the consumption of a glass of grapefruit juice with each meal. Moving away from the original idea that grapefruit contained special fat burning enzymes, in later time it was reported that grapefruit flavanones (in particular naringenin) reduced insulin levels, encouraging fat loss.
The actual reason that subjects following the later grapefruit diet experienced some weight loss may be more to do with a different activity of naringenin. The original grapefruit diet of the 1930′s suggested low carbohydrate intake which often shows increased weight loss in itself, by fluid loss.
Naringenin has an inhibitory effect on CYP1A2 dependent metabolism of caffeine in humans. When caffeine is ingested, in the case of the grapefruit diet, in coffee with grapefruit juice, the effects of Caffeine and the associated aid to fat burning are extended. By how much would depend on the naringenin content of the grapefruit juice.
It should be noted though that a grapefruit juice with typically 22-24% carbohydrate content will have approximately 12% fructose content. It could be considered that the use of grapefruit juice as an aid to weight loss is something of a contradictory measure.
We can conclude that whilst the flavanones in grapefruit may possess and impart useful mechanisms for both increasing insulin sensitivity and prolonging the fat burning effects of the methylxanthine, caffeine there is probably little point in using it at all outside of the simple consumption of fresh grapefruit as a foodstuff alone.