In 80s, we can say that if you wanted guaranteed weight loss, the grapefruit diet was the plan to follow. Providing no more than 800 calories a day, the grapefruit diet menu involved eating lots of 'fat-burning' grapefruit to kick-start your metabolism. It same as much black coffee as you liked, some daily protein (mainly boiled eggs) and the odd piece of dry toast.
At the time, nutrition experts dismissed it as another fad diet. They explaining that the 'fat-burning' properties of grapefruit were, in fact, a myth and any weight loss that occurred was due to the extremely low and potentially dangerous calorie intake.
But two decades on, it seems these nutritionists may need to rethink their views on the popularity of grapefruit as a 'diet food' if the results of a study published earlier this year to be believed. The latest research, the simple act of adding grapefruit and grapefruit juice to your diet, really can aid weight loss. But unlike the seriously restricted diet of the 80s, you get these results without changing what else you eat.
While this research might tempt you to fill up on grapefruit to boost your weight loss campaign, if you’re taking any medications you might want to speak to your GP first or check the literature that comes with your medication.
This is because a wealth of research shows that grapefruit juice can interact with a number of medications, potentially causing serious side effects. It works by inhibiting an enzyme in the intestines that’s responsible for the natural breakdown and absorption of many medications. When the action of this enzyme is blocked, blood levels of these medications increase and this can lead to potentially toxic side effects.
Research suggests that flavonoids and/or furanocoumarin compounds are the substances in grapefruit juice that block the enzyme in the intestines. Many drugs appear to be affected by grapefruit juice so if you are taking any medication, it’s essential to check whether you can safely consume grapefruit juice. In the meantime, it’s likely that grapefruit segments may also interact with certain medications so you’d be wise to consult your GP before eating lots of grapefruit. Other citrus fruits don’t seem to have any effect.
Grapefruit juice provides many nutrients, such as vitamin C and lycopene. But chemicals in grapefruit interfere with the enzymes that break down (metabolize) certain drugs in your digestive system. This can result in excessively high levels of these drugs in your blood and an increased risk of serious side effects.
The exact chemicals in grapefruit juice that cause this interaction aren't known. But these chemicals are present in the pulp and peel of grapefruit as well as in the juice. For this reason, any grapefruit products can interact with certain medications. Include dietary supplements that contain grapefruit bioflavonoids. If you avoid grapefruit, you may also want to avoid tangelos, a hybrid grapefruit, and
The study included 100 obese people who were divided into three groups. The first group ate half a grapefruit before each meal three times a day. The second group drank grapefruit juice before each meal. The third group received no grapefruit. No other changes were made to their diets.
After 12 weeks, those participants who ate grapefruit with each meal lost, on average 3.6lb. Only a third of a pound a week, but pretty good considering they didn't make any other changes to their diet. Meanwhile, those who drank grapefruit juice three times a day lost 3.3lb in the 12 weeks. By comparison, the grapefruit-free participants lost, on average, only 0.5lb.
But weight loss wasn't the only health benefit seen when grapefruit or the juice was consumed. The research also found the grapefruit-consuming participants had lower levels of insulin, a hormone that regulates blood sugar levels and fat metabolism, which in turn might help to reduce the risk of diabetes or stroke.
The researchers believe grapefruit contains unique plant compounds that reduce insulin levels, which in turn promotes weight loss.
The link between raised insulin levels and excess weight is complicated and multifaceted. To start with, high levels of insulin may indicate that sugar isn't efficiently utilised for energy with the result that it's more likely to be stored as fat. Secondly, high levels of insulin can make people feel hungry so that they eat more. And finally, high levels of insulin prevent the body from breaking down fat. Add these together, and it's easy to see why lower levels of insulin may promote weight loss. What exactly it is in grapefruit that has this insulin-lowering effect remains unclear.
Care needs to be taken when interpreting the results. It's the first study of it's kind and even the researchers believe more work needs to be carried out before recommendations are made regarding grapefruit intake. Fortunately, a larger study is already planned for later this year.
When it comes to reducing the risk of diabetes, experts also believe we should err on the side of caution before recommending vast amounts of grapefruit.
Nutrition experts also agree that more research is needed before rushing out to stock up on grapefruit. Most tend to agree with the nutritionalists of the 80s and say it's unlikely that grapefruit has any magical properties in terms of aiding weight loss in the absence of other diet or lifestyle changes. It's perhaps more likely that participant’s lost weight simply because they were taking part in a study and, as a result, were more focussed on their food intake and exercise habits.
From many source