The Science of Strength Training - Part 3
Good nutrition is a crucial part of a strength training program. Training with weights creates the stimulus; your diet provides the raw materials for building muscle. Eating the right foods will increase your energy levels, maximize your gains in the gym and improve your health. It will also provide the fuel and fluids needed for intense training, speed up your recovery after training, reduce fatigue and help achieve a healthy body composition.
Nutrition for Strength Training
Training diet
Aim to include portions of proteins, carbohydrates and good fats in your diet. You should also include about 20 – 30 grams of fiber per day in your diet. Vegetables like, broccoli, cauliflower, carrots, peas, pumpkin and salad greens are very important in your diet and also offer a fair amount of fiber. Don’t forget to also eat fruit, and drink about 8 glasses of liquid per day preferably water. Timing and portion sizes are also very important. I will discuss these points later on. You should consume smaller meals through the day, trying to have 3 whole food meals with 2 snacks. You should have breakfast, a mid-morning snack, lunch, a mid-afternoon snack and dinner. Spread these meals throughout the day eating every 2 ˝ to 3 hours.
Calories
The most important thing when it comes to building muscle is calories. To gain weight, you need to take in more calories than you burn. Scientists recommend increasing your usual calorie intake by 20%, which equates to about 500-700 extra calories for men and about 250-500 extra calories for women. These calories should come from a balanced intake of carbohydrates, proteins and fats. There are many various ways of calculating your daily caloric requirements, so I will leave that up to the individual personal trainer or fitness coach you are consulting with. There are 4 calories in each 1 gram of protein and carbohydrate and 9 calories in 1 gram of fat. 1 calorie equates to 4.2 kilojoules.
Cutting your calorie intake
To reduce your body fat, cut your calories by 15%. This relatively modest decrease minimizes any drop in your metabolic rate and allows you to retain your hard-earned muscle. The problem with drastically reducing your calorie intake is that you cause your metabolic rate to slow down. This is called the ‘starvation adaption response’ and means your body stockpiles fat and calories rather than burning them for energy so that it becomes harder and harder for your body to burn fat. Your glycogen stores also quickly deplete, causing fatigue, a drop in your performance, low energy levels and mounting hunger. Worse still you end up breaking down muscle tissue as well as fat to provide fuel. On the other hand, reducing your calories by a modest 15% will produce steady fat loss without sacrificing muscle. You can expect to lose about 0.5kg fat / week, slightly more when combined with some cardio activity. To lose 0.5kg of fat you would have to burn 3500 calories.
Carbohydrates
Carbohydrate, in the form of muscle glycogen and blood glucose, is the major source of fuel for strength training. Eating too little carbohydrate results in low muscle glycogen levels, low energy, reduced training intensity and fatigue. Carbohydrate also stimulates the release of insulin – an anabolic hormone that drives protein and carbohydrates into the muscle cells, encouraging muscle building. A low-carbohydrate intake causes protein breakdown and loss of muscle mass. On the other hand, eating too much carbohydrate in one meal or over the course of the day may result in unwanted body fat once the body’s glycogen storage capacity is exceeded. As a general guideline and remember that this is only a guideline, you should consume 5 – 7 grams carbohydrate/kg body weight per day, depending on your metabolism, body fat level and training volume. If you weigh 75kg, you would need a minimum of 375 grams and a maximum of 525 grams carbohydrates daily.
Which foods?
Choose mostly fiber-rich carbohydrates like potatoes, oats, rice, pasta, fruit, lentils and beans. Honey, dried fruit and fruit juice are denser sources of carbohydrates and make it easier to reach your daily carbohydrate needs if you have a fast metabolism. If you tend to gain body fat easily or have a slower metabolism, stick with natural fiber-rich carbs, which are more filling. Low-GI diets are beneficial for strength trainers as well as the general population. They can help control blood sugar levels, appetite, and body weight, lower blood fats, reduce the risk of diabetes and heart disease, and can help with cholesterol. A low-GI daily diet is important as it encourages glycogen recovery between workouts. It produces steadier blood glucose and insulin levels, which facilitates a steady uptake of glucose by the muscle cells for glycogen storage, and minimizes the conversion of blood glucose into body fat.
The best way to plan a low-GI diet is to balance each meal by including:
- a lean source of protein (e.g. chicken breast, fish, egg whites etc)
- a fiber-rich carbohydrate (e.g. a white starch, potatoes or pasta)
- vegetables (e.g. broccoli or green salad)
- a little unsaturated fat (e.g. olive oil dressing or nuts)
The Glycaemic index
The Glycaemic index (GI) is a measure of how quickly your blood glucose will rise after eating a portion of food containing 50 grams of carbohydrate. All foods containing carbohydrates are ranked on an index from 1 to 100 relative to pure glucose, which has the highest GI value of 100. Thus, high-GI foods produce a relatively rapid rise in blood glucose and low-GI foods produce a slower, more sustained rise in blood glucose. All carbohydrate foods have a Glycaemic index (a GI value) and these can be found on various web sites on the internet, they range from high GI (60-100), medium GI (40-60) and low GI (0-40). Many complex carbohydrates – such as potatoes, bread and rice – give a quick rise in blood glucose, while many simple carbohydrates- such as fruit – give a slower rise. It is important to realise, however, that the GI values relate to single foods being consumed. When two or more foods are eaten together their GI changes. High GI foods eaten together with proteins or fats moderate the glucose response, so the GI values only count for single foods. For example, potatoes cause a relatively rapid blood glucose rise. But if you eat potatoes with a high protein food (tuna) or a high fat food (butter), the GI will be lower and so your blood glucose will rise more slowly.