What, when and how much? Eating and exercise

nutrition coaching and advice in manchester

Ok, so firstly it’s important to note that the primary source of energy that our bodies use during exercise is carbohydrate. Our muscles contain enough stored carbohydrate for around 2 hours of high intensity exercise – therefore it is very important that regular exercisers eat a carbohydrate rich diet. Our bodies can also use fat for energy, however it breaks down a lot slower and so our bodies generally use carbohydrates as their main source of energy. Protein isn’t used much at all but if our carbohydrate stores deplete then our bodies may start to break down muscle to use instead. 

So, now that is covered, let’s take a look at what, when and how much we should eat of carbohydrate, protein and fat…


Now we know that carbohydrate is the key player during our exercise sessions, it follows that not eating enough of it can lead to reduced performance, intensity and recovery as well as earlier onset of mental and physical fatigue (I know – doesn’t sound fun). It can also increase your risk of injury because carbs have roles in the central nervous system so your coordination and concentration levels can drop (sounds even less fun!). Maintaining good stores of carbs in your body as well can actually help with hydration because carbs like to store themselves with water. So when we use those stored carbs, water is released as well. Anyone been on a low carb diet before and noticed rapid weight loss in the first few days? Yeah, that’ll be due to your carb stores depleting along with a whole bunch o’ water!!

Right, now you’re on board the carb train, let’s talk numbers.  For 3-5 hours per week of moderate intensity exercise like running, weight training, circuit classes or similar, 3-5g of carbohydrate per kg of your bodyweight per day is appropriate. For 5+ hours per week, 5-7g per kg of bodyweight per day would be ideal but that could increase to 10g if you are training heavily/very frequently/for a competition.

Before exercise:

So before we start exercising, we want to make sure our carbohydrate stores are optimised to avoid the issues I mentioned earlier. To optimise your performance, consume 2.5g of carbohydrate per kg of your bodyweight 2-4 hours before exercise. Depending on the time you have, you might only have time for a snack, in which case 1-2 hours prior to exercise is ideal. If opting for a full meal as well/instead, 3-4 hours prior is best. This ensures a steady supply of energy during your activity and will also allow time for your stomach to have settled after your meal/snack. Moving on to the kinds of carbs we should be eating before exercise then…

Heard of the Glycaemic Index? Or perhaps you have heard it abbreviated to GI when people call foods ‘low GI’ or ‘high GI’? Before exercise, we are looking to consume low GI carbohydrates, so your wholegrain foods like brown bread, rice or pasta – oats are a great one too. Beans and lentils are also low GI options you can throw in there. Choosing low GI will mean that you will be able to train for longer before you fatigue.

After exercise:

We need to replace the stored carbohydrate we have just used during exercise. If you train daily, it is even more important to do this before your next session otherwise we risk fatigue and a drop in performance. Optimal replenishment of your carbohydrate stores happens within the first 2 hours after exercise but it still occurs at a good rate for up to 6 hours post-exercise.

So, how much?

Within the first 2 hours after exercise, 1g per kg of body weight is recommended. Now high GI carbohydrates (like white bread, rice, potatoes and sugary snacks/drinks) are actually ideal here so that your body can use those carbs as fast as possible. You might be thinking, hang on, I’m sure I have heard that I should STAY AWAY from high GI? Well my friend, your metabolism is at its peak after exercise and your body is craving some sweet sweet carbs. If you fancy the occasional treat, now is the best time for it!  After that, within 2-4 hours post exercise, we’re aiming for around 50g extra (depending on what your overall carbohydrate goal is for a 24 hour period – reference the section ‘How much carbs’ to calculate this but if unsure drop me a message). Whether you should choose low or high GI here is still a topic for debate – personally if I have gone high GI straight after exercise I might go low GI here but that’s just a personal preference and it fits around my meals etc.


As a population, many in the UK consume far too much protein as a proportion of the rest of our intake, mainly due to meat-heavy diets and the huge protein supplement trend in the form of shakes, bars, and various ‘health products’ that add an extra dash of protein for ‘better health’.

Now don’t get me wrong, protein is still a very important part of our diets and, while exercising, arguably more so especially if your goals involve fat loss, muscle gain or are performance-based.

Meeting your body’s protein requirements will firstly prevent muscle loss (which can occur if requirements are not met), as well as aiding in muscle repair and growth. The amount of protein that you should be consuming will depend on the type of activity that you do.

  • For low to moderate intensity exercise like brisk walking or slow cycling, 1-1.2g of protein per kg of bodyweight is recommended.

  • For moderate to high intensity exercise like jogging/running, skipping, rowing then 1.2-1.6g per kg of bodyweight is your goal.

  • Sports like football, basketball, hockey, dancing , tennis – basically anything that’s intermittent in nature, 1.4-1.7g per kg of bodyweight is your target range.

  • If participating in strength, power training or looking to bulk up then 1.6-2g of protein per kg of bodyweight is recommended. 

So, we’ve established how much, but what about when we should be eating this protein?

You might have heard people talking about allll the protein they’re gonna load up on after a workout so they can maximise those GAINZ. Now the theory behind that is partly right; you definitely should eat protein after exercise, but downing 6 raw eggs (~78g of protein) is not the way to go. There is no way your body could actually use all of that and if it can’t use it, it is simply removed from your body in urine. Also, excessive intake can lead to your body losing Calcium which can lead to osteoporosis and it can also cause dehydration (kidneys have to work harder due to all the protein being thrown at them and they are thirsty workers).  Keeping hydrated is of course important for us all, but also key for fat loss so if that is your goal, keep an eye on this.

A great way to make sure your body gets a constant supply of protein across a 24 hour period (and therefore maximizing those gains/repair/recovery of your muscles) is splitting your intake up into 4 portions per day. That way, your body actually has a chance of using a larger proportion of the protein that you’re consuming.

As our bodies aren’t using protein as a main source of energy during exercise, there’s not much benefit of having a protein heavy snack or meal prior to exercising, so I would plan your 4 intakes around that. However, during sleep is when your body will go to town on growth and repair so before bed is a decent time to get some protein in ya.


Before exercise: Our bodies digest fat relatively slowly and so eating a fat-rich meal prior to exercise can be detrimental to performance as the carbohydrate digestion is then slowed down and can’t reach our muscles as fast. So limiting the fat content of your pre-workout meal/snack is a good idea.

After exercise: It is a similar story after exercise too, as we don’t want to slow down the digestion of carbs or protein. We want them to get to our muscles as fast as possible. Fat is still an important part of our diets and stored fat can be used for energy as mentioned earlier, but simply isn’t the body’s fuel of choice (You may have heard of people that use high fat diets to fuel exercise but that is a whole other topic and for the majority of us, using carbohydrates as our primary fuel and protein for growth and repair is the way to go).

One last thing…

This post has been very much looking at fitting your main macros (carbohydrate, protein and fat) around exercise and it is easy to get this confused with the total number of calories you should be eating and what kind of split of each macro you should aim for depending on your goal. If you haven’t already got this mapped out and you feel like perhaps you’re not quite giving your body what it needs, do reach out and we’ll have a chat.

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Ray Hickford

Hi, I’m Ray, a health and wellbeing professional in Manchester working with clients through training and nutrition programmes to help them feel more confident, strong and happy both in and outside of the gym.
As a Qualified Personal Trainer and Level 4 RSPH Nutrition Advisor, I am constantly learning myself - from my clients, from other industry experts and sometimes myself! And sometimes I write some of this down for ya.

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