Overweight and obesity increase the risk for diabetes.

It is reported in a study, that modest weight loss reduced the risk of developing type 2 diabetes by about 60%. In the group that was monitored, 7% weight loss was achieved through modification of diet and 150 minutes per week of physical activity.

(Diabetes Prevention Program Research Group: reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002; 346; 393-402)

Food allergies

There is so much to be said on this topic. We have tried to simplify it and to discuss it during different phases. Please contact us that we could help you to eat a balanced sports diet that would optimize your performance.

Sports nutrition could be simplified to 4 different phases during which different goals want to be achieved. The first phase is the last meal before an event; the second phase is the nutrition during the event. The third phase is the recovery time immediately after the event and the fourth phase is the fuelling time between exercises and events, when the time between the events is at least 24 hours.

1. Last meal before an event

Competing in a fasting state is not advisable. Eating a low GI carbohydrate before an event could prevent you from hitting the wall and running out of energy.

It is observed that a single low GI meal before exercise increase the contribution of lipid oxidation to energy production with consequent sparing and extended availability of glucose sources during exercise.

In the first few minutes of exercise, blood glucose levels can drop dramatically and in some cases, fall below normal levels of blood glucose. This is referred to as rebound hypoglycaemia, lasts no longer than a few minutes, and is irrelevant to the availability of glycogen stores for exercise. Some athletes are very sensitive to low blood glucose levels during exercise and this phenomenon could affect their performance. In many studies blood glucose levels at 15 to 30 minutes during exercise were lower after high GI than after low GI pre-exercise feeding.

2. Nutrition during an event

The feeds that is needed during an event, depends on the length of exercise.

If the exercise last up to 40-60 minutes, no additional ingestion of carbohydrates are needed. It takes time before carbohydrate is absorbed and transported to and used by muscle as a fuel. Some research have indicated, that a small intake of carbohydrates, or even rinsing the mouth with a carbohydrate containing drink, could give a mental enhancement that improves performance.

In an event lasting longer than 40-60 minutes, ingestion of high GI carbohydrates can enhance performance. Drinking/eating about 60g of a combined fuel source of glucose:fructose or maltodextrine:fructose:sucrose, per hour is recommended.

When an event lasts longer than 2 hours, an amount of up to 90g/h may be preferred. When such high rates of carbohydrates is ingested, it should consist of a mix of multiple transportable carbohydrates, such as glucose : fructose or maltodextrine : fructose.

Keeping hydrated during exercise is as important as eating the right amount and source of carbohydrates. Major disturbances of cell volume have profound effect on cellular metabolism. Cell swelling will favour anabolic actions, such as protein synthesis and glycogen synthesis. Drinking too little fluid will encourage these reactions to proceed in the opposite direction.

There is no substantive evidence that protein taken during an event would improve performance or endurance. There are a number of studies that indicates that a small amount of protein taken during exercise may help decrease the muscle soreness that accompany a long bout of exercise.

3. Recovery time, immediately after an event

This is the ideal window of opportunity during which the body can recover at its best. It is important to eat enough high GI carbohydrates and a small amount of low fat proteins.

The immediate ingestion of high GI carbohydrates is associated with higher muscle glycogen concentrations. The high GI foods could be replaced with carbohydrate supplements made up of glucose or maltodextrins solutions, which allow the fastest possible rate of absorption and delivery to the muscle.
In this short-lasting phase of recovery, the muscle uptake of glucose can proceed independently of the presence of insulin and is more active when muscle glycogen at the end of the exercise is low. The aim of the food intake at this time would be to obtain the fastest rate of glucose delivery to the muscle.

4. Fuelling between exercise

The fuel that the body requires between training events or competitive events would come from the carbohydrates (pasta, bread, rice, rice, etc.), the proteins (milk, eggs, chicken, etc.) and your fat (canola/olive oil, avocado pear, nuts, etc.) consumed throughout the day.

It is estimated that on average a well fed athlete would have up to 2000 calories (8 400kJ) of stores carbohydrates in the form of glycogen and glucose. In addition we have 80 000 calories (336 000kJ) worth of energy in the form of fat! Therefore, running out of fat stores is not a worry. Just continue using moderate amounts of heart healthy fats. Looking at these facts, one could see that it is very important to make sure that your glycogen stores are filled up before an event; thus carbo-loading is very important before an event lasting longer than 60 minutes.

The amount of carbohydrates needed depends on the intensity and duration of the training or event. See the table below.

Food with a lower glycaemia index (low GI) is the preferred source of carbohydrates between exercises. Low GI carbohydrates take longer to digest and have a slower raise of blood glucose; this slower, sustained source of energy need less insulin. Physiologically spoken, the lower GI carbohydrates put less strain on the body than higher GI carbohydrates.

Protein in the form of chicken, meat, fish, eggs or milk products are high quality proteins, help with protein synthesis during the recovery period. Our protein need could increase to 1.2-1.7g/kg body weight with endurance and resistance-trained athletes. This protein intake is easily reached with a normal balanced diet. If you are worried that you don’t use enough proteins, ask your dietitian to calculate your daily intake. It is not necessary to use a protein shake if you eat a healthy balanced diet.

Studies focussing on endurance and resistance training have shown eating as little as 10g of protein after an event would achieve a worthwhile effect of muscle growth, repairs and adaptation following the exercise stimulus. A protein intake higher than 20-25g is not recommended.

Whey protein provides a rapidly absorbed high-quality protein source that is often used in supplements. A small serving of whey protein is needed which makes it practical to use after exercise. Dairy products, such as milk or yoghurt, would also increase your whey intake as a recovery feed.

Practical Nutritional Recommendations for the Athlete, Ronald J. Maughana _ Louise M. Burkeb
aLoughborough University, Loughborough, UK; bSports Nutrition, Australian Institute of Sport, Canberra, ACT, Australia

IAAF Booklet, based on the IAAF International Consensus Conference held in Monaco April 2007, updated June 2011

Sports Nutrition Mallorca Conference 2011, booklet

Nestlé Nutrition Institute, Does a Carb-Protein Combination in Sports Drinks Increase Endurance?