Understanding the Glycemic Index

UNDERSTANDING THE GLYCEMIC INDEX & GLYCEMIC LOAD.

Introduction.

In relation to physique enhancement & weight loss, the scientific community has focused on counting calories for many years. Then, it focused on fat, & the “low-fat diet” movement was born. For the past few years, however, the focus has moved onto carbohydrate ingestion/restriction. Because of advances in nutritional biochemistry, many physiologists (as well as people wanting leaner physiques) have learned that various types of carbohydrates affect the body differently.

Interestingly, some types of carbohydrates are preferentially converted to fat, raise blood glucose levels into the danger zone, & are linked to many health problems like diabetes, cancer, obesity etc. Other types of carbohydrates are not converted to fat easily & are not considered harmful to good health.

To understand the differences between the various types of carbohydrates, it’s good to have a knowledge of the “glycemic index” & the “glycemic load”, & how they are related.

THE GLYCEMIC INDEX.

The glycemic index was developed by Dr. David Jenkins in 1981 & was primarily used as a tool for diabetics looking to control their blood glucose (blood sugar) levels. Today, many other non-diabetic individuals are also using this index as a way to choose foods to eat for health, weight loss & performance.

On the index, carbohydrates that are listed below 55 are more slowly absorbed & subsequently cause a small increase in blood sugar & insulin. Quite simply, the glycemic index is a numeric ranking of carbohydrate-containing foods based on their potential to raise blood sugar levels. Carbohydrates that are high on the index (above 70), are quickly digested & absorbed. These carbohydrates tend to cause a rapid rise in blood glucose &, in most cases, a quick rise in insulin.

On the other side, carbohydrates that are low on the glycemic index (55 & below) are more slowly absorbed & therefore cause a relatively small increase in blood sugar & insulin. Hence, the GI index allows an individual to indirectly estimate both blood glucose & insulin levels. This is important for diabetics & anyone looking to help control their weight. It’s also good to determine what types of carbohydrates to eat around exercise workouts for improved performance.

HIGH GI FOODS.

Generally speaking, foods that rank high on the glycemic index include products made from finely ground flours like bread & baked goods, processed breakfast cereals, baked, mashed & French fried potatoes, snack foods like chips & pretzels, & sticky rice. Foods that rank lower on the glycemic index include most fruit & vegetables, sweet potatoes, minimally processed foods like oatmeal, oat bran, barley, bulgur wheat, long-grain brown rice, pasta & dairy products. What follows is a list of some common carbohydrate foods & their glycemic index:

HIGH GI (70+) :

Boiled potato – 101

Baked potato -85

Pretzels – 83

Corn flakes – 80

Shredded wheat – 75

Cheerios – 74

Bagels – 72

Watermelon – 72

White rice – 72

MODERATE GI (70-56):

Croissant - 67

Brown rice – 66

Wholemeal bread -65

Raisins – 64

Ice-cream – 61

Bran flakes – 61

Sucrose – 59

Coke – 58

Fruit cocktail -55

LOW GI (55-):

Wheat bread – 53

Potato chips – 51

Peas – 51

White pasta -50

Apple Juice – 40

Oranges – 40

Skimmed milk – 32

Whole milk – 27

Fructose – 20

Peanuts – 13

HOW DO NUTRITION RESEARCH SCIENTISTS WORK OUT THE GI OF A FOOD?

Researchers measure out a portion of food that contains 50 grams of carbohydrate. For example, 4 ½ slices of bread, 1 ¼ cups of rice, 1 ½ pounds of carrots, & 3 medium apples contain about 50 grams of available carbohydrate. A food is fed to a group of test subjects & their blood sugar responses are measured. – The test subjects’ blood sugar response to the food is then compared to their response to eating 50 grams (about 3 tablespoons of glucose) of pure glucose.

To illustrate this point, I’ll look at oatmeal. Oatmeal on average, is approximately 49 on the GI index. This means that when plain oatmeal that contains 50 grams of carbohydrate is eaten, it will produce an increase in blood sugar approximately 49% of that obtained when the same amount (eg 50 grams) of pure glucose is consumed.

There are, however, some flaws with the glycemic index. So whenever you consider using the glycemic index as a guide, the glycemic load should also be considered:

GLYCEMIC INDEX Vs GLYCEMIC LOAD.

The glycemic load uses the glycemic index as well as the actual amount of carbohydrate (eg the serving size) to determine the overall effect of a carbohydrate-containing food in relation to blood sugar & insulin levels.

As mentioned previously, the glycemic index compares different food sources that contain carbohydrates of the same quantity (eg 50 grams of glucose is compared to 50 grams of carbohydrate in oatmeal). However, this is not always practical or realistic because many foods are not consumed in 50 gram portions.

So, the glycemic load is calculated by multiplying the amount of carbohydrate in a given serving of food by the glycemic index of the same food & then dividing that number by 100.

How about a ‘real-life’ example. – A boiled potato has a glycemic index of around 101. A Mars chocolate bar has a glycemic index of around 65. Just looking at the glycemic index, you might assume that the Mars bar is the ‘better’ choice of the two options. However, the average serving of a baked potato is about 150 grams, which contains 17 grams of carbohydrate. – A mars bar serving size is only 60 grams but contains 40 grams of carbohydrate. – Therefore, the Mars Bar has the greatest glycemic load & has a larger effect on blood glucose & insulin. The boiled potato has a glycemic load of 17, while the mars bar is 26. So even though the potato has a higher glycemic index, the mars bar has more effect on blood glucose despite being half the size!

So, in conclusion, both the glycemic index & the glycemic load provide information relative to the impact that carbohydrate has on the blood sugar & insulin response. However, the glycemic load is a much more practical scale. It’s also important to remember that the glycemic index & glycemic load only refer to the food when it is eaten alone. When you add some fat or protein to a meal containing carbohydrates, the total impact of either score goes down. So it’s wise to take glycemic load into account, but don’t be a slave to it! It’s just one of the many factors to consider when planning an effective diet.

Carbohydrate Cycling

CARB CYCLING.

At the most basic level, carbohydrates are ‘sugar’. This may sound confusing, but the end result of eating either a bowl of rice or a spoon of sugar are the same – glucose. When both are processed in the body, the final result is the same – they’re both broken into glucose, which is the body’s best source of energy.

The only energy source for the brain & nervous system is glucose, unlike the muscular & skeletal systems. Also, carbohydrates (glucose) are the body’s most immediate energy source & have a 30-50% faster rate of breakdown compared to fat. Anaerobic exercise relies exclusively on carbohydrates through glycosis. Carbohydrates also have a protein sparing effect, which keeps the body from breaking down protein for energy.

Essentially, carbohydrates come in two forms, simple & complex. Simple carbs are mono & disaccharides or “sugars”. Fructose, the naturally occurring sugar in fruit, sulcrose (table sugar), & lactose (the naturally occurring sugar in dairy products) are some examples of simple forms. Complex carbs are things like rice, potatoes, pasta & bread. These carbohydrates are polysaccharides or “starch”. They contain long chains of more than 3,000 glucose molecules linked together.

Regardless of the form (except for fibre), the body converts carbohydrates into energy, - glucose. The main difference between simple & complex carbs is the amount of time it takes the body to convert them into glucose. Complex carbs tend to give a more gradual & sustained energy release. Simple carbs give an immediate energy release usually accompanied by a sharp decline in energy as well. For this reason, it would be best to have more complex carbohydrates earlier in the day to provide a more prolonged energy supply. Have simple carbs after your workouts & exercise sessions for quick glycogen replenishment. Remember to keep in mind the glycemic index & load of the food sources.

One thing to realize is that once the carbohydrates you have eaten have been converted to glucose, what is not used to fuel body functions & replenish muscle glycogen is shuttled into fat stores. Usused carbohydrates will make you fat! Your main goal with carbohydrates is to provide enough energy to fuel body functions& muscle activity each day - & ‘no more’. Therefore the variable is carbohydrates, if protein & fat intake remain the same each day.

The Carb- Cycling Process.

Carbohydrate cycling is a diet strategy that many fitness competitors & bodybuilders use in order to prepare for a show. This tactic can also be used by anyone wanting to shed bodyfat. When your intake of carbohydrate is low, your body is forced to use stored bodyfat for energy. Also, when your body has been given plenty of carbs, it uses them rather than fat as the energy source.

The body does require a certain amount of carbohydrates to carry out basic processes – such as brain function & the nervous system. I wouldn’t recommend going much lower than 120 grams of carbohydrates per day for this reason. If your diet is too low in carbohydrates, your workouts & training are going to suffer. Anaerobic activity is fueled by carbohydrates. Also, you can fall into a state of ‘ketosis.’

Ketosis is a state of carbohydrate deprivation & should be avoided. Ketone bodies are the product of incomplete burning of fats. When these are present in the blood, your body doesn’t have enough carbohydrates available in order to properly metabolize bodyfat. In other words, you need carbs to burn bodyfat! The body can use ketone bodies instead of glycogen for energy production, but they are no where near as efficient in fueling exercise.

When you are in a state of ketosis, you become irritable, sluggish & may become dehydrated. Without carbohydrates available in the body, your body breaks down protein for additional energy ( a catabolic state). Your body will actually metabolize muscle tissue for energy at about the same rate as fat if you don’t have enough protein intake. Your hard earned muscle will be metabolized. – This is obviously counterproductive for someone trying to build or maintain lean muscle mass.

The correct way to carb cycle is to make sure you are taking an adequate amount of protein & not limiting your carbohydrates to the point of ketosis. Ketosis can be monitored for by using ketosis strips. These strips can be found at many pharmacies & chemists & contain a special chemical that will change colour in the presence of ketones in the urine. The container will have a scale on the label, with blocks of colour to compare to the strip. You check for ketosis by passing the strip through your urine. The ketosis strip will turn a certain colour after about 15-20 seconds.

I’ve found the best way to do this is to follow a plan that consists of three low-carb days & one high-carb day. You continue to cycle the days until you reach your desired goal. The high-carb days are important for a few reasons. Firstly, it throws your metabolism off & tricks your body into thinking it has come off the diet. If you continue to have low-carb days, your body will eventually adapt to this & slow its metabolism down to compensate for the lower caloric intake. This is known as’ homeostasis’, - your body trying to maintain a balance. Having a high-carb day ‘fools’ the body. But, after a longer period of time, your body will adapt to the three low-carb days & one high-carb day as well.

Another reason to have high-carb days is to replenish glycogen stores. Glycogen is the body’s storage form of carbohydrates found in the liver & muscles. Since glycogen is combined together with water, the extra volume in the muscle cells causes the muscles to appear larger. Muscles deprived of glycogen are small & flat whereas muscles full of glycogen are big & full. I’m sure most people would prefer the latter!

The final reason to have high-carb days comes from a health standpoint. After following a strict low-carb diet for three days in a row, you can become mentally & physically drained. For this reason, you should give your body a break from the routine every fourth day. After the high-carb day, you will again feel full of energy, more alert & ready to go into the next three days.

After doing the carb cycling for 4-6 weeks, you should reevaluate what progress you have made. If you’re getting close to your desired bodyfat, you may want to cut back to two low-carb days & one high-carb day. This will prevent your body from adapting & slowing down its metabolism. You could even cycle low, moderate & high carbohydrate days to ‘throw’ your body off. When you have reached your desired bodyfat level, you can alternate low-carb & high-carb days, or even have ‘moderate’ carb days all week long. The best measure of progress is how you look in the mirror & how you are feeling. The scales, tape measure & bodyfat percentage can only say so much.

I have outlined a sample low & high carb day that can be used. The high-carb day also incorporates higher glycemic index carb sources. If you get hungry in the middle of the night on the low-carb days, I’d recommend having a scoop of protein to keep you going until the morning. When it comes to fat loss, carbohydrates are the variable. After you have reached your desired goal, you can follow more general guidelines that will become a part of your everyday lifestyle.

LOW-CARB DAY.

Meal 1: 5 egg whites, 2 yolks. 4oz. turkey burger, 8 strawberries or a pear.

Meal 2: 6oz. chicken breast, half cup of oatmeal.

Meal 3: (Post-workout) 2 scoops of whey protein, half tbsp lecithin granules.

Meal 4: 6oz. chicken breast, 2-3 cups of mixed green salad, 1tbsp olive oil & vinegar.

Meal 5: 6oz. chicken breast, 1 cup of broccoli or green beans.

Meal 6: 4oz. turkey burger, 5 egg whites, 1 cup of vegetables for the omelet.

Meal 7: 1-2 scoops of casein protein, 1 tbsp flaxseed oil.

HIGH-CARB DAY.

Meal 1: 9 egg whites, 1 cup of oatmeal, half cup of raisins.

Meal 2: 6oz. chicken breast, 1 cup of oatmeal, 1 banana.

Meal 3: (post-workout) 2 scoops of whey protein, half tbsp lecithin granules.

Meal 4: 6oz. chicken breast, 1 cup of brown rice, 1 cup of broccoli or green beans.

Meal 5: 6oz. chicken breast,6oz. baked potato, 1 cup of mixed green salad, 1 tbsp olive oil & vinegar.

Meal 6: 4oz. turkey burger, 5 egg whites, 1 apple or pear.

Meal 7: 1-2 scoops of casein protein, 1 tbsp flaxseed oil.

WEEKLY CARB-CYCLING PLAN SAMPLE.

Sunday: Low

Monday: Moderate

Tuesday: Low

Wednesday: High

Thursday: Low

Friday: Low

Saturday: High

When used correctly, I believe that carb-cyling can be a very effective way of losing bodyfat while preserving your muscle mass.