Sunday, October 4, 2009

Why Low GI makes you feel full and can help reduce belly fat

Eating a low GI (glycemic index) meal will keep you feeling fuller for longer, King’s scientists have discovered in what could be the key to how the GI diet works.

Researchers from the Department of Nutrition and Dietetics in King's College London have found that low GI (glycemic index) meals increase gut hormone production which leads to the suppression of appetite and the feeling of fullness. This is the first study to provide clues as to how a low GI meal produces satiety.

When you read ‘low GI’, also read protein and fat.  When you read 'carbs' only think green leafy and colourful vegetables.  

A low GI way of eating is also a high fat, healthy way of eating. For example, healthy fats, not trans fats or bad fats need to be a part of your diet. Nuts, olives, avocado, cream, meats, cheeses are all considered high fat, but they’re also low GI.  Think about the French way of cooking – lots of cream, plenty of meat but no starch and no sugar and all in small portions. This way of eating – like the Mediterranean way – is what keeps us fuller for longer, halts the insulin resistance process and in turn reduces the middle weight gain.    Meat and other fatty carbs like avocado, nuts and eggs actually don't have a GI - better still for a healthy filling diet.

I don't know about you, but I've no desire to 'diet'.   The word diet conjures up that feeling of being hungry.   I can't function when I'm hungry and the only way I feel good, focussing on what I have to do and happy within myself is with a diet loaded with good fats.

The trick is to stay fuller for longer.
GI is a ranking assigned to carbohydrates according to their effect on the body’s blood sugar levels. Remember, all carbohydrates when broken down create blood sugar.   A low GI meal takes longer to digest and releases sugar into the bloodstream more slowly than a high GI meal. A low GI diet is known to cause reduced appetite but the mechanisms behind this have so far remained unknown. To address this Dr Tony Leeds, Senior Lecturer in Nutrition and Dietetics, and Reza Norouzy at King’s College London looked at the effects of a single low versus high GI meal on gut hormone levels in 12 healthy volunteers.

Each participant ate an identical medium GI meal for dinner, fasted overnight, and was given either a low (46) or high (66) GI meal for breakfast. Blood samples were then taken every 30 minutes for 150 minutes, and levels of the gut hormone GLP-1 and insulin measured. GLP-1 is a hormone produced by the gut that has been shown to cause a feeling of fullness and suppression of appetite.

Volunteers who ate a low GI breakfast had 20 per cent higher blood plasma levels of GLP-1 and 38 per cent lower levels of insulin compared to those who had consumed a high GI breakfast. These results show for the first time that eating a low GI meal increases GLP-1 production and suggest a physiological mechanism as to why a low GI meal makes you feel fuller than a high GI meal.

Determining the GI of foods
To find out what foods are high or low GI, head to The GI is measured against 100, as glucose and it’s affect on blood sugar is the benchmark. A low GI is a food ranked at 40 and below. Mid GI is 40 to about 60 and above 60 is considered high GI. The sugar you consume will be the key culprit in the accumulation of fat around the middle. This also means that we need to be very wary of fruit. It’s been said that fruit is "nature’s candy".   Tasty, and we think it's healthy, and to a degree and taken very sparingly it is.   But overdosing on the fruit, a lot like overdosing on fruit juice, is not going to do our blood sugar level any good.    For example, we may think that munching on dates is nice and healthy - their GI is 110 - way too much sugar.

Go very easy on it and if you’re in the habit of loading up your plate with a pile of fruit for breakfast, could be well worth reconsidering. You’re in effect starting your day with a sugar load and can almost guarantee you’ll be hungry by mid morning.

Finally, what's the consequences of a high GI diet?
Eating high GI all the time will constantly spike your blood sugar and will put your arteries into spasm. (See Dr Ray Strands 'Releasing Fat').    A high GI diet is a sugary one.  It includes starchy vegetables, lots of fruit, breads, pastas, rice, confectionary, cakes, biscuits, desserts, alcohol, some chocolate (not all), many grains and refined foods containing white flour.    We eat sugar and it's natural response is to make us hungry again very shortly after eating it and we need another sugar hit.   We don't crave salt or fat when we eat a lot of sugar, the body craves the next hit of sugar just as it would the next hit of niccotine.    With the constant swings of high and low crashes throughout the day we're consuming way too many empty calories to keep ourselves going.    What happens then?   It literally opens the pathways to disease - diabetes, cancer and heart disease to name a few.    We get cranky, irritable and don't know why.    At work we lose concentration, get foggy headed and can become listless.    Weightgain is an inevitable result and in the dangerous middle area.  

Out of all the diets out there, the one message that we need to take home out of this is - sugar is the biggest killer.   It's the one thing responsible for so many middle age problems of weight and disease.   So cut it out - and live long and strong.

Professor Peter Emery, Head of Department of Nutrition and Dietetics, and one of the paper’s author’s comments: "The findings of this study are an important first step in understanding how low GI foods can help to address issues of weight control and what part they should play in a balanced diet."

Source: King's College London Press Release 18 Mar 2009

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