Most runners know they need to eat a combination of healthy carbohydrates and protein soon after a run to kick-start recovery. But what if you don’t feel hungry straight away after a run? If you wait too long for your appetite to return after a long run, you will delay recovery. It takes at least 20 to 24 hours of refuelling with carbohydrate-rich foods to replenish your muscle stores fully, so daily workouts can leave you running on low fuel levels. Since the effects of dehydration and muscle glycogen depletion can be cumulative, inadequate refuelling can contribute to overtraining syndrome (when you push your body beyond its capability, resulting in fatigue, injury, a weakened immune system and mood changes).
A loss of appetite is quite common after intense exercise. It happens, in part, because running causes the hypothalamus gland (the brain’s hunger centre) to release some of the same neurotransmitters that tell you you’re full after a meal. Hunger is also suppressed when there are high levels of amino acids and fatty acids in the blood, as is the case after exercise, due to the mobilisation of these nutrients to provide energy during running. High-intensity running increases plasma amino acid levels more than low-to-moderate-intensity running, which may explain why it is better at suppressing hunger.
The longer you wait to eat, the less glycogen you store and the longer it takes to recover. There’s a window of 30-60 minutes when the body is receptive to getting carbs back into the muscles. Your muscles are most receptive to reloading glycogen in the 15-30 minutes immediately following exercise because blood flow to muscles is enhanced during this time. Muscle cells can pick up more glucose and are more sensitive to the effects of insulin, a hormone that promotes the synthesis of glycogen by moving glucose out of the bloodstream and into cells. So it’s vital to take in an adequate amount of carbohydrate – and protein – as soon after exercise as possible.
Insufficient fuelling and refuelling, pre and post run, can also lead to weight loss. Although a low bodyweight and low body-fat level are associated with better running performance, it’s important to recognise that losing weight will not guarantee success and may lead to health problems. In both men and women, being underweight can lead to an increase in illness, injury and fatigue, while in women low body fat also causes a drop in oestrogen levels. A fall in oestrogen leads to disturbances in the menstrual cycle and amenorrhoea (cessation of monthly periods), which can result in a loss of bone minerals and a reduction in bone density. In younger (premenopausal) women, this is called osteopenia (lower bone density than normal for age), which is similar to the osteoporosis that affects post-menopausal women, where bones become thinner, lighter and more fragile.
In the 30-60 minutes after a run, you may be able to boost the rate at which your muscles store glycogen, as well as speed up the recovery and repair of muscle tissue, by eating protein in combination with carbohydrate. Drinks (liquid meals) are easier to consume when you’re not hungry. Believe it or not, good old-fashioned skimmed milk is one of the best recovery foods out there. It not only provides carbohydrate and protein in the ideal 4:1 ratio, but it also has the advantage of containing calcium, riboflavin and magnesium. The protein in milk helps to rebuild muscle tissue and research suggests it may reduce exercise-induced muscle damage. Smooth and semi-liquid foods may be better tolerated than solid foods if you’re feeling queasy after a run. Try yogurt, porridge, rice pudding, custard or puréed fruit. Bland foods, such as rice cakes or instant porridge, are also good.
If you’re looking to gain weight, experts advise lowering the intensity and volume of your training by ten to 15 per cent and eating a little more. You may also need to adjust your training programme to include short periods of lower-intensity training and more rest. For an indication of your daily calorie requirements, you will find a useful formula here, which takes into consideration your weight and activity levels.