This week I take a look at the strategies I have come to adopt in terms of the composition and the timing of my food intake in a run programme. As always, I will try to illustrate the concepts and how they are applied rather than prescribe specific recommendations that may not fit within the paradigm in which the runner reading this blog may operate.
Concept 1: Metabolic Flexibility
It is important to remember that we evolved to go through periods of high and low availability of fuel. We are not a mechanical engine designed to run on a fixed amount of fuel at regular, fixed, intervals. We are incredibly flexible organisms designed to respond to the environment we are placed in. The holy grail for all exercise and nutrition scientists is to figure out how we capitalise on our natural evolutionary capacities and alter the environment, to maximise our response.
Metabolic flexibility refers to our ability to switch between carbohydrate and fat as the predominate fuel source supplying our energy needs. As we evolved, our ability to metabolise fat would have been most advantageous during lean periods and provided us with great endurance to cover long distances at low intensities. This ability is also key to performance in endurance events. If an athlete always fuels their body with carbohydrate, at regular intervals, their body never has reason to switch to fat as a fuel source.
Metabolic Flexibility in Training
To develop metabolic flexibility, I regularly train after an overnight fast. On a Sunday, I will often sleep a little later than normal, have a coffee and head for my long run. I have built my long-run to a point now where I can run at the required intensity comfortably for 15-miles in the fasted state. As this run is ~1hr 45 minutes, I am pretty confident that I have developed the capacity to utilise fat as a fuel source quite well. By lunchtime on Sunday, I may not have eaten for 18-hours, ~two hours of which I have been running.
This approach is not just for low to moderate intensity running. I can complete intense sessions (6 – 8 miles in length) after an overnight fast, the main reason being I am fasted not depleted. However, it is also important to practice intake prior to intense work-outs a) so you maintain the ability to metabolise carbohydrates efficiently and b) so that it is not unusual on race day. I always eat before my Wednesday session which takes place in the afternoon.
Metabolic Flexibility Day to Day
Many people will have grown up with the notion of breakfast being the best meal of the day. There is no direct evidence for this. It can be, but it depends on the circumstance. For example, if someone is attempting to lose weight, a breakfast that prevents them from snacking on sugary foods mid-morning or overeating later in the day, could be useful. However, encouraging individuals to delay breakfast and increase the time they are in the fasted state could also be useful. During the working week, I eat breakfast at work. This often means I will train or start work at 6:30 / 7:00 am and not eat until 9:30am meaning I may be 14 – 15 hours in the fasted state.
During the off-season, when training volume is lower and socialising is higher, I have experimented with a two meal per day strategy. At the outset, this practice can seem strange or extreme but in reality our bodies are designed to adapt and I always try to experiment particularly when training volumes are lower. In practice, this means waking up a bit later, having a coffee and not eating until lunch before continuing on with the day. These strategies during high volume training will almost certainly leave you lethargic and often ill.
Concept 2: Variability, a runner’s best friend
It’s true for injury and mounting evidence suggests its true for diet. Metabolic flexibility works both ways. I don’t exclude any one food, I do try to eat predominately food that once roamed the earth, grew from the ground, fell from a tree or swam in the sea or as my kiwi colleague Professor Grant Schofield calls it – food with low human interference (HI). In recent years, I’ve tried to increase my carbohydrate intake from fruits and vegetables because they come with more vitamins, minerals and fibre than say for example plain pasta. I’m conscious that I eat wholegrains (porridge, Weetabix) for breakfast so I’ll try to have a chicken or fruit salad with Greek yoghurt at lunch. Conversely, if it is a pre-workout lunch, I could simply have a white bread banana sandwich. Snacks comprise largely of fruit and nuts (almonds) as and when needed.
For dinner, I might have chicken and mixed vegetables in a tomato based sauce but equally I might have a large pasta based meal on the eve of a weekends training that I know includes a hard work-out Saturday and a long run Sunday. Other nights, I might have an omelette with cheese, bacon and spinach, sans-carbohydrate. The need for variability and my training load are the key drivers but convenience also plays a role. My house-mate and I alternate the cooking 4 days a week so the bottom line is a healthy, home cooked meal without becoming overly obsessed.
Concept 3: Habit formation (consistency is king)
As the training phases progress, I can get a little less-specific. In practice, I find a month of really thinking about it and getting it right means I can lose any excess weight without any compromise in training intensity. I find once your weight is down and your training well, you can afford to loosen the regime to what suits a bit more without any weight regain. This is assuming you are training well and still drawing from a variety of naturally occurring sources.
As with training, overall consistency of good practice is what counts not bursts of obsession. For example, when running a PB in November 2016 I weighed ~86kg; when running a PB 7-months later I weighed 84kg and currently I weigh ~83kg. I cannot attribute this to any strict dietary practice rather almost 2 years of training and adaptation to a specific activity without interruption.
Until 2-weeks’ time – enjoy your running – don’t obsess unless it’s about consistency.
Peter Francis 