THE GI DIET
The glycaemic index (GI) is a measure of the speed with which carbohydrate foods affect blood sugar levels. The most important principle for maximising energy levels is to mainly eat foods which are lowest on the GI chart, and restrict or avoid foods which score high on the chart.
By doing this you can also reduce cravings for particular foods and reduce the need to overeat. High GI foods have been shown to increase appetite. This leads in turn to the craving to eat more of these carbohydrate foods, perpetuating the downward spiral. One interesting study gave two groups of people 200 calories of sugar to eat before letting them loose two hours later on a banquet at which they could eat as much as they wanted. On average one of the groups ate 476 calories less than the other group at the feast. What was the difference? The sugar that was given to the group who ate less calories was fructose (fruit sugar) which has a very low GI of 22, while the other group were given glucose which has a GI of 100. This probably explains why a couple of hours after eating a filling Chinese meal it is often the case that people complain that they are hungry – rice and noodles have relatively high GI. Other studies have backed this up. In one study, obese teenage boys were given one of three breakfasts – a high GI meal of instant oatmeal, a medium GI meal of whole oats, or a low GI meal of a vegetable omelette and fruit. Later in the day the voluntary calorie intake after the high GI meal was 53 per cent greater than it was for the medium GI meal, and 81% more than after the low GI meal.
This is an abbreviated GI chart for quick reference, but for a full chart see my book Maximising Energy.
|
HIGH G.I. 71-100 |
MEDIUM G.I. 51-70 |
LOW G.I. 15-50 |
|||
|
RESTRICT |
MODERATE |
ENJOY |
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|
Sultana bran |
71 |
Orange juice |
52 |
Yoghurt, low fat |
14 |
|
Puffed wheat |
74 |
Kiwi fruit |
53 |
Fructose |
22 |
|
Pumpkin |
75 |
Sweet potato |
54 |
70% cocoa solid chocolate |
22 |
|
Chips |
75 |
Banana |
54 |
Full fat milk |
27 |
|
Donut |
76 |
Sweetcorn |
55 |
Lentils |
29 |
|
Rice cakes |
77 |
Oatmeal biscuits |
55 |
Butter beans |
31 |
|
Vanilla wafers |
77 |
Buckwheat |
55 |
Dried Apricots |
31 |
|
Plain biscuits |
77 |
Durum wheat spaghetti |
55 |
Skimmed milk |
32 |
|
White bread |
78 |
Meusli |
56 |
Pear |
37 |
|
Broad beans |
79 |
Mango |
56 |
Whole-wheat spaghetti |
37 |
|
Jelly beans |
80 |
Kellogg’s Mini-wheats |
57 |
Apple |
38 |
|
Rice Crispies/Cornflakes |
82 |
Honey |
58 |
Plum |
39 |
|
Baked potato (old potato) |
85 |
Porridge (oatmeal) |
61 |
All-bran |
42 |
|
Cooked carrots |
85 |
Beetroot |
64 |
Orange |
44 |
|
Lucozade |
95 |
Sucrose |
64 |
Chickpeas |
45 |
|
French Baguette |
95 |
Raisins |
64 |
Yakult |
45 |
|
Cooked Parsnips |
97 |
High fibre rye crispbreads |
65 |
Grapefruit Juice |
48 |
|
Dates |
99 |
Grapenuts |
66 |
Baked beans |
48 |
|
Glucose |
100 |
Nutri-grain |
66 |
Peas, green |
48 |
|
Maltodextrin |
105 |
Pineapple |
66 |
Raw carrots |
49 |
|
Maltose |
105 |
Mashed potato |
70 |
Pumpernickel bread |
50 |
What influences the effect that foods have in GI terms is probably quite complex and is a sum total of the types of carbohydrates, combined with the fibre content, the protein content and the fat content. While the GI was developed in 1981, it is only in very recent years that we are coming to fully understand the effects that individual foods have within the context of the whole diet. For the most part the foods which have an impact on blood sugar levels and which are highest on the chart, are fairly obvious such as most sugars which have a speedy impact. But there are some surprises such as potatoes, carrots, pizza and maltodextrine (a processed starch used in vast quantities by the food industry in many packaged foods). For instance potatoes have a GI which is similar to that of sugar. Does that make potatoes a bad food? If you are prone to energy and blood sugar problems then they are best moderated, however they are a valuable source of nutrients while sugar is simply a source of empty calories, with no nutrients, and is best limited by everyone.
There are differences in grains with those high in a starch called amylopectin, such as wheat, corn and most types of rice, being faster-releasing that those high in the other starch, amylose, such as barley, rye and quinoa and brown Basmati rice. A pleasant surprise is barley which is one of the lowest GI grains and cooks like rice, making it an easy, and delicious, substitute. One reason why legume foods, such as lentils and soya, are so low down on the scale is that they contain a substance which slows the digestion of amylose and so reduces its impact on insulin further.
The processing of foods also makes a difference. Take the same bag of wheat and turn it into pasta and it will have a lower glycaemic index than if you turn it into bread. Studies have shown that wheat, corn and oats increased on the GI when they went from the whole grain, to cracked grains, to coarse flour to finely ground flour (these were not refined grains, stripped of fibre and nutrients, but simply increasingly ground grains). The GI concerns itself with averages because, for instance, under-ripe bananas score 30 making them a low-GI food while ripe bananas score 54 making them a medium-GI food. The reason for this is that when they are under-ripe starch 80-90 per cent of the carbohydrate content is starch, but as they ripen this changes to free sugars. Depending on the type, rice ranges from 38-93 and potatoes from 47 to 95.
Fruits and vegetables have different effects depending on their sugar make up. Fruits which have higher amounts of fructose, fruit sugar, have a slowish effect on blood sugar as it needs to be converted into glucose. However some fruits have significant amounts of glucose in their make up along with the fructose. These include grapes, pineapples, watermelon and very ripe bananas. This means that, for instance a banana might be a good option if you have just been jogging and need a glucose top-up, but if you have blood sugar problems it may be give you too quick a ‘hit’. This does not make bananas a bad food, but you would be best combining them with, for instance, porridge oats to slow down their impact. An even better option would be grated apple with the porridge. You may find that so called sugar-free foods are sweetened with grape juice, which is tantamount to adding glucose, while others use apple juice, which is does not have such a direct effect on blood sugar.
There are also differences in different brands of certain foods. For instance soya milk, which is made from very low GI soya bean, is usually quite low, however the manufacturing process can mean that there are significant differences in the carbohydrate content of different soya milks. If they are unsweetened or sweetened they can range from 4-36 grams of carbohydrates per 8oz (225 ml) of product. This will affect the GI score. Dairy-milk is between 11-13 grams of carbohydrates per 8pz (225 ml), however the lactose found in it has a higher GI than the carbohydrates found in soya milk.
Vegetables can be a surprise in the blood sugar control stakes. Most vegetables are very low on the glycaemic index and are encouraged as the mainstay of most meals (I know you are saying yummy, spinach for breakfast!). However most of the root vegetables are quickly turned into sugars when they are cooked. The best illustration of this is when you realise that so much of the world’s supply of sugar comes from the sugar beet, which is a type of beetroot. When you bake a carrot or parsnip they caramelise easily and you realise how sweet they are.
Once you understand the basics of the way in which the G.I. diet works you can make some easy choices to balance you blood sugar levels. Here are some of them:
|
INSTEAD OF FAST-RELEASING HIGH G.I. FOODS |
CHOOSE
SLOWER RELEASING G.I. FOODS |
| White bread, ‘brown’ bread | Wholegrain rye bread |
| White rice | Brown Basmati rice, Barley, Quinoa |
| Rice cakes | Rye crackers, Oat cakes |
| Cornflakes, Rice puffs | Porridge, Muesli, All-bran |
| Jam | Nut butters |
| Cooked parsnips, carrots, beets, potatoes or Swede |
Cooked yams, sweet potatoes, or corn (mid GI). Raw root vegetables, Butter Beans, Flageolet beans, peas |
| Dates | Dried apricots, Fresh fruit |
| Milk chocolate | 70% cocoa solid chocolate |
TOTAL MEAL EFFECT
Choosing foods which are lower on the GI is the first place to start if you want sustained energy. However, it is also necessary to remember that the total meal combination - in other words the balance of proteins and fats to carbohydrates on your plate - affects blood sugar balance.
To refresh your memory insulin is the hormone which lowers blood sugar, while glucagon is the hormone which raises blood sugar and it is a balance between these two that is sought. Carbohydrate foods eaten on their own, especially fast-releasing ones, result in a large insulin response and a small glucagon release.
Protein foods tend to result in a small and equal release of insulin and glucagon. This means that they have little impact on blood sugar levels directly. However if they are eaten alongside carbohydrates, proteins have the effect of making the glucagon to insulin release a little more equal.
Eating fats on their own has no direct response on either hormones, but they do slow down the impact that carbohydrates have on insulin. Some ‘sinful’ foods seem tantalisingly acceptable on the GI but this is because of their fat content. For instance Mars Bars which have 9 teaspoon of sugar in an average bar, are tempered in their effect by the high fat content. A packet of crisps, which consists of potato flour which would normally be around 95 on the GI is lower because they are so high in fat. This does not make them ‘good’ foods. Pizzas remain an anomaly and have been shown in research to have a more dramatic impact on blood sugar than would be expected. When compared to high GI foods they found that while both triggered a high initial response, pizza continued to create this response after blood levels started coming down of the participants eating the comparable foods. Pity the poor pizza eaters!
The effects of the various elements of our diet on insulin and glucose are as follow:
| INSULIN | GLUCAGON | |
| Carbohydrate | ***** | No change |
| Protein | ** | ** |
| Fat | No change | No change |
| Carbohydrate and Fat | **** | No change |
| Protein and Fat | ** | ** |
| High Protein and Low Carbohydrate | ** | * |
| High Carbohydrate and Low Protein | ******* | * |
Quite a number of people follow the principles of food combining, or the Hay diet, where they do not mix ‘dense’ proteins and ‘dense’ carbohydrates at the same meal (‘dense’ means that the food consist of more than 80 pr cent protein or carbohydrate). While this way of eating is highly beneficial for people with digestive problems it is not the way to balance blood sugar levels. You can see from the chart above that eating carbohydrates on their own, or carbohydrates with a minimal amount of protein, would release a lot of insulin with little opposing glucagon. Following the Hay diet and eating such meals twice per day would certainly exacerbate insulin resistance in susceptible people. For this it is ideal to eat some proteins alongside carbohydrates at each meal to stabilise blood sugar levels. The food combining principle can achieve this if adherents eat meals consisting of a little protein, such as fish, chicken, eggs, meat or soya foods, alongside a lot of vegetables. However if the food combining follower ends up eating meals which are heavily biased towards lots of ‘dense’ carbohydrates such as rice, pasta or bread, with no protein to balance it out then this can play havoc with blood sugar levels, and therefore energy levels.
Eating meals which combine carbohydrates and proteins has also been shown to be the best support for the stress/adrenal system. Because of the critical part that the adrenal hormone system has to play in maintaining energy levels this is another reason to favour this way of eating if your energy levels are flagging. The important thing to remember is to eat low GI foods, mainly vegetables, fruits, pulses, beans, soya and some grains such as rye and barley alongside proteins for the best effect.
FREQUENCY OF EATING
While aiming to stabilise blood sugar levels it is important to pre-empt the possibility of blood sugar lows. The way to do this is to eat small, frequent meals. This does not necessarily mean eating more, but it does help if you can spread the food out over five or six small meals instead of eating two or three large ones. By doing this, and by making sure that the snacks are those which do not have a negative effect on blood sugar balance, you can increase your energy levels many fold. It is common for busy people to skip breakfast, or even for people to believe that they are not hungry at this time, and this is the first major mistake that is made. It is also often the case that hunger signals are over-ridden by drinking a strong cup of coffee in the morning. After ten to twelve hours without food your body needs fuel and it is no wonder that skipping breakfast is the first step in ensuring that blood sugar levels swing up and down wildly all day. Even if you are in a rush you have time to grab a couple of pieces of fruit, a small yoghurt and some oatcakes, and if necessary take them with you.
MORE THAN JUST BLOOD SUGAR LEVELS
High GI goods do not just dent your energy levels. They also activate more insulin which activates a substance, called HMACoA reductase, which causes the liver to make more cholesterol. In this way high GI foods, and other blood triggering substances such as alcohol, indirectly affect cholesterol levels adversely. Low GI foods have been shown to promote ‘healthy’ HDL cholesterol over ‘unhealthy’ LDL cholesterol. High GI foods also play havoc with blood sugar control, and this leads to increased oxidation of tissues including the arteries. These explains the relationship between Syndrome X and cardiovascular risk.
And believe it or not, if you eat non-refined foods, you will also be contributing to the health of the planet, as well as your own health, by maximising energy resources. Processing a golden field of wheat into a sugary breakfast cereal takes considerably more energy than turning it into wholewheat bread. If everyone switched their diets towards unrefined foods the energy savings would be huge.
SUMMARY OF HOW TO ADDRESS BLOOD SUGAR PROBLEMS WITH DIET
The way to regulate blood sugar levels, is to eat little and often in order to pre-empt a blood sugar lows, avoid foods which are converted too quickly into glucose, and to concentrate on eating foods which are rich in starches, or complex carbohydrates. It also helps to have some proteins alongside the carbohydrates.
It is ideal to eat three moderate meals, and two between-meal snacks along with a snack before bedtime. The main points are:
For an in-depth look at how to improve your energy levels and beat addiction read Maximising Energy. Click here for more information