Exercise - what to eat!
This blog is about what to eat (or not!) when exercising, with a particular focus on losing weight. This is a topic much debated and as with all things to do with nutrition there is plenty of misinformation and flawed advice out there...
Carbohydrates aren’t essential to fuel exercise
One of the most common misconceptions around diet and exercise is the flawed calories in and calories out model, where people think that exercise uses up a certain number of calories which helps weight loss by creating a calorie deficit compared to the calories coming in from their food. Summed up in the standard ‘move more, eat less’ thinking on weight loss.
So the conventional wisdom is that if you eat a bowl of cereal with 300 calories you would need to run for around 30 minutes to burn these calories off. And if you exercise harder or longer then you will go into a calorie deficit and therefore reduce some of your excess fat. The human body is however just not that simple, as the type of food coming in has a huge effect on hormones in the body, particularly insulin, which affects what the body does with different foods. This is not a challenge to the law of thermodynamics but a recognition that the human body is a complicated system with many different ways to gain, use and store energy.
Our bodies can get energy from two types of fuel - glucose which comes directly from sugar and carbohydrate or ketones which we get from dietary fat or make from our own body fat if our bodies are in the right hormonal state to do this. The right hormonal state for fat burning is when our blood sugar is well controlled and we are not on a dietary carb/sugar glucose roller coaster of eating frequently, feeling hungry all the time and relying on glucose for fuel. Being ‘fat adapted’ so our bodies can actually access our fat stores, and not be reliant on sweet or starchy food coming in at regular intervals, is the optimum state for weight loss.
Once we are in this hormonal state, there really is no need to ‘carb load’ and fuel up for exercise, as per the prevailing wisdom. We will be able to access our energy stores as and when we need them – be that sitting at desk tapping away on a laptop, going for a walk or running a parkrun. This is also the state we should strive to get into if we have excess fat to lose as it will allow us to go longer without feeling the need to eat, avoid the blood sugar roller coaster and encourage our body to use our own fat stores for energy.
If you need some inspiration about what can be achieved physically with a lower carb diet then take a look at Chris Froome, three times Tour de France winner who adopted this way of eating to lose weight and become a winner:
Fasting and exercise
Once we are fuelling our bodies with real food that is light on refined carbohydrates, keeping us off the glucose roller coaster, doing exercise in a fasted state is a great way to exercise. So in my (non Tour de France!) world this means doing a 9am parkrun on a Saturday morning without eating anything beforehand.
I have seen my own fitness improve and my run times come down now I have starting doing parkrun more regularly and in a fasted state. See below for a chart I am feeling proud of with my parkrun times declining this year:
If you are really into understanding how best to fuel your body on a low carb diet, especially if you are training for a more strenuous event, then I would recommend this book – The Art and Science of Low Carbohydrate Performance by Volek and Phinney:
https://www.amazon.co.uk/gp/product/0983490716/ref=ox_sc_act_image_2?smid=A3P5ROKL5A1OLE&psc=1
Finally a short YouTube film and scientific paper for any remaining doubters about the benefits of exercising in fasted state. 100 miles run over 5 days with zero calories coming in, from Steve Bennett and Ian Lake, a couple of my PHC (Public Health Collaboration) buddies:
https://www.youtube.com/watch?v=ejnGMQW0yOA
https://type1keto.com/zero-five-100/
What to eat after exercise
Think real food (as usual!) especially foods that are higher in protein and contain healthy fats, skipping the refined carbohydrate, for example:
Nuts
Cheese
Cold meats
Tinned fish
Eggs
Avocado
I am about to start experimenting with making a low carb, keto friendly, protein bar for post-exercise consumption which I will post up on social media and on my website when I have cracked it! Most of the ones you can buy are super sweet and really not great for low carbers or people looking to lose weight.
For some good advice on hydration and replacing salt after exercise check out this article: https://www.dietdoctor.com/fasting-and-exercise-protocol
Helping weight loss with a CGM trial
I am now doing Continuous Glucose Monitor (CGM) work with clients that is really helping them understand their own body’s responses to different foods, and exercise, and pinpointing the changes they should make to lose weight or gain better blood sugar control.
If you would like to know more about using a CGM for self-experimentation then please do get in touch and I would be happy to support and coach you through this. As always I offer a free initial online meeting to discuss if this approach could be right for you, which you can book directly by following this link or just drop me a message to make a date: watch-your-waist/discovery-meeting