Ask the Experts - Nutrition

Answers from Andrew Hamilton:

Q. Dear Andrew,

I would like to know how many grams of carbs (p/kilo of bodyweight) we require for weight/fat loss. Correct me if I'm wrong but I understand the equations are:

• To gain mass, 1.6-1.8 grams of protein per kilo of bodyweight per day and 3grams of carbohydrate per kilo of bodyweight per day
• To maintain lean mass, 1 gram protein per kilo of bodyweight and 2 grams of carbohydrate per kilo of bodyweight per day

Can you please confirm that these equations are correct?

Thanks,

Steve Jennings.

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Dear James

Although it’s a simple question, there’s no simple answer I’m afraid! This is partly because the effects in the body of protein and carbohydrate intakes cannot be considered separately, partly the because your carbohydrate requirement is very much a function of your energy expenditure and also because different people often respond differently to various feeding protocols.

Let’s take the protein question first; most studies have shown that 1-2g per kilo of body weight per day fulfils the needs of almost all athletes. There is some evidence however that compared to endurance athletes, strength and power athletes seeking to gain and maintain maximum muscle mass can benefit from intakes at the upper end of this range.

Having said that, it’s also important to understand that protein requirements can be affected by carbohydrate intake too; high levels of energy expenditure without ample carbohydrate to fuel this activity increases the amount of protein consumed for energy, which in turn can lead to muscle mass loss. This is because muscles contain relatively high amounts of the branched chain amino acids (BCAAs), and BCAAs can easily be utilised as a ready source of energy when carbohydrate is in short supply during vigorous activity. This means that any athlete seeking to build or gain muscle mass must ensure that he or she consumes ample carbohydrate, even if the protein intake is sufficient. In this respect, 3g per kilo per day of carbohydrate may well not be enough. Consider a 70kg running 10 miles; the approximate calorie burn will be around 1000 calories. If he or she consumes 210g of carbohydrate (3 x 70), that’s only around 840 calories’ worth – not really enough to replace the energy expended during the workout, let alone provide the energy surplus required to regenerate and rebuild muscle tissue after hard training. As a rule of thumb, for any given athlete, not only should the total calorie count increase with increasing energy expenditure, but the ratio of carbohydrate:protein should also increase. However, getting the right balance to achieve your goals may take some experimentation and best way of achieving this is to monitor your food intake, weight and body composition until you achieve the desired results.

Andrew Hamilton BSc Hons MRSC