Fasting and training
It’s a question that’s been raised to me by a few people – can you combine a fasting diet with training for a sport?
Well yes, you can. But it requires some thought.
It is possible to continue training and follow a fasting/calorie restriction diet. You just have to be sensible. Planning a long run in marathon training for a fasting day simply isn't clever, nor is getting into the pool if you know you tend to feel light-headed on a fast day.
So for your reading pleasure, these are some of the things you need to think about/consider.
Train early - if you're used to exercising first thing in the morning, then make the most of the previous day's intake and train early. Your energy stores will be somewhat depleted by the overnight fast (also known as sleeping...), but less so than later on during a day of fasting.
Train late - if you simply can't face the thought of training on an empty stomach, wait until you've had something to eat. This depends on how you disperse your calories during your fasting day - if you spread them throughout the day, then it probably doesn't matter when you train - your exogenous (from food you've eaten) fuel levels will be consistently low. If you still have a 'main' meal during which you eat the majority of your day's calories, perhaps consider training a little while after that meal.
Hydrate - fasting encourages the utilisation of stored energy, and this process often also involves the elimination of stored water. Avoid dehydration by drinking regularly throughout the day - this may also help to stave off hunger pangs, and is essential for enabling quality athletic performance.
Eat well - If you have a poor quality diet in general, then the further restriction on fasting days could simply lead to nutrient deficiencies and poor health - less food = less calories, but it also means less vitamins and minerals. It’s important the you make up for the fasting days by eating nutritious foods on your feeding days. This is particularly important if you are stressing your body with training.
Be clever in scheduling - it simply makes sense to plan your most intense training days to coincide with 'feeding' days. You can exercise on fasting days, but it's likely to be a less than optimal performance.
It may feel like you're giving it 100% (and you may well be), but 100% on a fasting day is unlikely to resemble 100% on a feeding day. It feels hard because your body is struggling, and you're less likely to experience the gains you would expect from a well-fuelled training session.
Train smart, train well!
Refuelling? It's difficult to refuel properly on fasting days, and it's worth bearing in mind that refuelling isn't just about replacing spent energy, but about feeding your muscles so they can recover from your workout. It's what happens in this recovery phase that determines the benefits you see from your training - becoming faster, stronger, developing stamina - all are affected by recovery. Another reason not to plan intense training days to coincide with fasting days.
Don't fast on race day! Let common sense prevail - if you're racing, give your body the fuel it needs.