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Home :: Muscle Building Nutrition :: Carbohydrate

Carbohydrate

Carbohydrate, in the form of muscle glycogen and blood glucose, is the major source of fuel for strength training. You need to eat enough to fuel your workouts. Eating too little results in low muscle glycogen levels, early fatigue in the gym, reduced training intensity, slower gains and an increased breakdown of muscle proteins. Eating too much results in unwanted body fat. As a general guideline, you should aim to consume 5-7 g/ carbohydrate/kg body weight/day.

How much carbohydrate exactly?

Carbohydrate recommendations for the general population and endurance athletes are usually expressed as a percentage of total daily energy. For example, the International Conference on Foods, Nutrition and Performance in 1991 recommended that carbohydrates provide 60-70% of daily calories for most athletes This method focuses only on the ratio between carbohydrate and fat and works best for endurance athletes with high energy needs. For strength athletes, however, this method works less well as they require less carbohydrate than endurance athletes to fuel their workouts. In other words, they don't deplete their muscles of glycogen to the same extent that endurance athletes do. Bear in mind too that strength trainers tend to train different muscle groups every day so their muscles have plenty of time to recover. That's why it is more accurate to calculate your carbohydrate requirement according to the muscles' needs rather than your total calorie intake. Carbohydrate needs for strength trainers should therefore be given in terms of grams per unit of body weight and hours of training.

For moderate-intensity training lasting up to one hour, you should aim to consume 5-7 g carbohydrate/kg body weight/day. This range is suitable for everyone following any of the programs described in weight lifting programs. However, if you do additional training for a specific sport or you average 2-4 hours of moderately intense training daily, you should aim to consume 7-10 g/kg body weight/ day.

Example:
For a 75 kg male weight trainer:

Carbohydrate needs = (75 x 5)-(75 x 7) = 375-525 g/ day

What type of carbohydrates should strength trainers eat?

Carbohydrates can be grouped in different ways. The traditional method divides them according to their chemical structure - simple (sugars) and complex (starch and fibre) - but it is more meaningful for strength trainers to group carbohydrates according to their glycaemic index (GI). This is a measure of how quickly your blood glucose will rise after eating a specific amount of a given carbohydrate.

All foods containing carbohydrate are ranked on an index from a 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. Figures 16.1-3 show the GIs of various foods, divided into high, medium and low GI foods. According to this index, 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 realize, however, that the GI values relate to single foods being consumed. When two or more foods are eaten together, the GI changes. High GI foods eaten with protein or fat moderate the glucose response, so the GI values matter more when eaten alone. For example, if you eat potatoes on their own, your blood glucose level will rise quickly. If you eat the potatoes with a high­protein food (e.g. tuna) or a high-fat food (e.g. butter), the resulting GI will be lower and so your blood glucose will rise more slowly.

Low GI diets are beneficial for both strength trainers and the general population, I They can help control diabetes, lower blood fats, reduce the risk of heart disease and control body weight. For strength trainers a low GI daily diet is particularly important for encouraging glycogen recovery between workouts. It produces more steady 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 or cottage cheese).
• A nutrient-rich carbohydrate (e.g. potatoes or pasta).
• Vegetables (e.g. broccoli or green salad).
• A little unsaturated fat (e.g. olive oil dressing or nuts).

Eating a mixed meal like this evens out the effects of the high GI carbohydrates.

There are times, however, when high GI carbohydrates may be beneficial for strength trainers: when they are eaten immediately after a workout they replenish glycogen more quickly.

Should I eat carbohydrate before training?

Most of the research on pre-exercise meals has been with endurance athletes. In these studies, those athletes who consumed approximately 1 g carbohydrate/kg body weight about one hour before exercise were able to keep going longer than those who consumed nothing. However, the benefits of eating before strength training are less clear. It really depends on your goals - whether you are mass-building or trying to lose body fat ­and on your personal preference.

If you are mass-building and not trying to lose fat, a pre workout carbohydrate drink or snack may give you a little more energy to train. The more sets you do, the more stimulation your muscles receive, so this may help you perform a few more sets at the end of your workout when fatigue would normally set in. However, if you are trying to lose fat, skip that pre-workout drink or snack. Your body will then burn a little more fat during the recovery periods to replenish the fuel systems.

By working out without pre-workout carbohydrate you theoretically force your body to dip into its fat stores. One study at Appalachian State University, North Carolina, found that pre-workout carbohydrate (1 g/kg body weight) had no effect on the ability to perform strength training exercises. Those weight trainers who consumed a high­carbohydrate diet prior to working out were not able to lift more weight than those who did not eat extra carbohydrate. It seems, then, that it is your overall daily diet that is more important for fueling your workout.

But there is a downside. Exercising on an empty stomach may result in earlier fatigue and, if your muscle glycogen stores become depleted, you will break down more protein (muscle). Certainly, low-carbohydrate dieting will reduce your performance and produce progressively smaller gains in the gym.

If you feel more comfortable training after a snack and it does not impede your workout, there is no reason not to continue. It may prove your performance. If your goal is to fat, then training on an empty stomach well as cardio training) will help you to achieve this goal a little faster.

Should I consume carbohydrate during training?

There is certainly lots of evidence that consuming carbohydrate during exercise lasting more than one hour improves Endurance and performance. Blood glucose levels are maintained for longer and fatigue is delayed. But does this apply to a strength-training workout lasting less than one hour?

Researchers at California State University ave ten male weight trainers either a liquid meal (a meal replacement product (MRP) shake containing carbohydrate, protein and a little fat) or a placebo immediately before and during an intense weight-training workout lasting two hours). Those who had consumed the liquid meal maintained higher blood glucose and insulin levels throughout the workout, which - conclude the researchers could promote even greater muscle growth. This is because insulin increases the uptake of amino acids into muscle cells and reduces protein breakdown - the ideal state for muscle hypertrophy. Although the workout in this study lasted longer than one hour, it is possible that carbohydrate or carbohydrate/protein liquid meals during a shorter workout may be beneficial too.

A study with cyclists also found that drinking a carbohydrate drink before and during a time trial lasting approximately one hour improved performance time. It is possible, therefore, that consuming a carbohydrate-containing drink during a strenuous strength-training workout lasting 45-60 minutes may encourage faster muscle growth and offset or delay fatigue, giving you a little more energy to perform those last few sets. It may also reduce the risk of excessive protein (muscle) breakdown during the latter stages of your workout, which is a clear advantage.

If you wish to lose body fat or prevent fat gain, make sure you don't consume excessive carbohydrate during your workout. Many 'energy' drinks are high in calories so, if you drink a lot of them, you can end up taking in more carbohydrate than you burn off!

When should I eat carbohydrate after my workout?

Eating carbohydrate immediately after training is definitely beneficial for endurance athletes. Many studies have proved that eating within two hours of exercise speeds glycogen recovery and can improve your performance if you work out the next day. But the exact timing of your post-workout snack has always hung in the balance. Recent research presented at the Experimental Biology 99 conference, Washington, D.C., suggests that waiting one hour after training may result in greater muscle size and allow your body to burn more fat after training. In this ground­breaking study, researchers gave strength trainers a carbohydrate-protein drink immediately, one hour or three hours after a strength-training workout on three separate occasions. They found that protein manufacture was highest when the drink was taken either one or three hours after working out - there was no difference between these two times. Therefore, waiting about one hour after training before having a carbohydrate-protein shake seems like the best strategy for promoting muscle growth and burning fat.

Which is best: high fibre or low fibre?

Aim to get the majority of your carbohydrates from 'whole' foods, that is, foods which have undergone minimal processing and are as close to their natural state as possible. These foods, generally, have a higher content of vitamins, minerals and dietary fibre. For example, whole grains such as wholemeal bread, porridge oats, whole grain pasta and wholemeal flour have a higher content of B vitamins, iron and dietary fibre compared with processed or 'white' versions.

There is one downside to these higher-fibre foods if you have very high-calorie and carbohydrate needs: bulk. These foods can be very filling and you may find it difficult to eat enough food to satisfy your calorie and nutritional needs. For example, it is more filling and takes longer to eat four apples (48 g carbohydrate) than to drink a large glass (480 ml) of apple juice (48 g carbohydrate). Similarly, a large bunch of grapes (150 g) is more filling than a tablespoon (30 g) of raisins, yet both supply 21 g carbohydrate. So, to reduce the bulk of your diet, choose foods with either a lower fibre content (e.g. fruit juice instead of fruit; white pasta instead of wholemeal) or a lower water content (e.g. dried fruit instead of fresh fruit).

What should I eat after my workout?

For glycogen replenishment the obvious choice would be to consume carbohydrate. However, several studies have found that combining carbohydrate with protein is a more effective strategy than consuming carbohydrate alone. A study at the University of Texas at Austin found that a carbohydrate-protein shake (112 g carbohydrate plus 40 g protein) accelerated glycogen restocking in the muscle by 38% compared with carbohydrate-only drinks.

Protein combined with carbohydrate stimulates insulin release more than carbohydrate alone, which promotes faster uptake of glucose by the muscles cells and faster glycogen storage. Protein-only drinks fail to increase muscle glycogen, so save them until later or, better still, add some carbohydrate to them to make them more useful.

However, the benefits of a post-exercise carbohydrate-protein supplement don't stop there. A further study at the University of Texas at Austin found that such supplements taken after strength training also promote greater growth hormone (GH) release. Thus, the combination of higher insulin and GH levels create the ideal anabolic (muscle­building) environment. Carbohydrate-plus­protein also improves your mood state after training. Researchers at Ithaca College, New York, carried out a psychological survey on weight trainers after consuming either a carbohydrate-protein drink or meal, a carbohydrate-only drink or a placebo drink, Those who consumed the carbohydrate­protein combination, either in liquid or solid form, experienced less mental distress, less irritability and less fatigue than the others.

Aim for a balance of 2-3 times as much carbohydrate as protein in your post-workout snack or drink. A good rule of thumb for strength trainers (based on the mixtures used in the studies) is 20-40 g protein plus roughly double that amount of carbohydrate. Small amounts of fat can also reduce the rate of glycogen storage so make sure your recovery snack is low in fat. Some ideas for suitable post-workout snacks are given in the box below.

Is carbohydrate loading beneficial for bodybuilders?

Competitive bodybuilders sometimes use carbohydrate loading to increase muscle size and fullness before a competition. Whether this really is beneficial is debatable. In one study, researchers measured the muscle girth of nine male bodybuilders before and after a control and a high-carbohydrate diet. This carbohydrate-loading diet involved three lays of heavy weight training on a low­carbohydrate diet (10% calories from carbohydrate), followed by three days of light weight training on a high-carbohydrate diet (80% calories from carbohydrate). The control
diet involved the same weight-training program but the men ate a standard diet providing the same number of calories. So what happened? Carbohydrate loading did not increase the muscle circumference in any of the bodybuilders, which suggests that it probably has no benefit after all.

Obviously, this is just a single study so its not conclusive. There is plenty of anecdotal evidence from experienced bodybuilders that carbohydrate loading before a competition improves muscle fullness. If you decide to try this regime, however, you may achieve equally good results by omitting the three-day depletion phase and simply eating a high-carbohydrate diet for the three days prior to competition.

What should I eat between workouts?

To promote efficient recovery between workouts, you should divide your food intake into several small meals - ideally all with a low glycaemic index value. Frequent feedings tend to produce more stable blood sugar and insulin levels, promote efficient glycogen storage and increase the metabolic rate. So, for optimal muscle-building and fat-burning effects, you should consume approximately six balanced meals or snacks throughout the day. Each meal should include 1-2 portions of carbohydrate-rich foods and at least 1 portion of a protein-rich food. Include plenty of vegetables with at least two of your daily meals, and eat a minimum of three portions of fruit each day.