I remember one thing from when I was a junior athlete at Track & Field Nationals. Not the race, not the medal ceremony. It was the intense hunger I felt waiting in the warmup tent, just 10 minutes before the start of the race. I also remember feeling thrilled to find a Rice Krispy square in my bag and quickly stuffed it into my mouth. Lucky for me, by race time I felt fuelled and ready to run.
The high carbohydrate, processed nature of a Rice Krispy square can work in short order but, why was I so hungry in the first place? Like many young athletes, I didn’t give much thought to the components of my diet like fibre, protein, different types of carbohydrates, and whether there are the benefits for the timing of certain nutrients. My diet consisted of a lot of cereals, breads and pastas and I was not particularly concerned whether they were whole grain or refined and whether I was getting enough protein.
To maximize training, competition, and recovery, it helps to know about how our bodies process nutrients so that we can make the best choices. A couple of key concepts are important when thinking about how to fuel for performance, not just the idea of getting enough calories. Different macronutrients are digested at different rates and the level of processing of certain foods can be used to benefit your training and recovery.
Carbohydrates Are Digested First
Runners need carbohydrates. Carbohydrates (excluding fibre) are the most efficient sources of fuel for your muscles. However, if you eat a lot of carbohydrates in the form of boxed cereals, packaged granola bars, and fruits and don’t understand why you feel hungry so quickly, read on.
Sometimes the issue is just not having enough calories but, how quickly the body digests certain foods can also be a factor. The type of macronutrient you eat (carbohydrates, proteins, fats, and fibre) will determine how fast your stomach empties and how satisfied you feel after a meal. Carbohydrates leave the stomach first, followed by fat and protein. This sequence is determined by the fact that the stomach is the primary location for protein digestion. Fibre will also slow down the digestion of food and help make you feel more satisfied.
The Thermic Effect of Food
The thermic effect of food refers to the differing amounts of energy expended by your body during the processing of certain macronutrients. The thermic effect of protein is the highest at 20–35%, followed by carbohydrate at 5–15%, and fat at 2–3% (expressed as a percentage of macronutrient energy content).
Importantly, the level of processing of a meal also impacts how much energy is needed to digest it, independent of its macronutrient content.
A 2010 study by Barr & Wright showed that our bodies can extract calories more efficiently from a processed cheese sandwich with white bread and processed cheese compared to a sandwich with wholegrain, seedy bread with real cheddar cheese. The number of calories used for digesting the processed sandwich was only about 11 per cent versus 20 per cent of the less processed sandwich’s total energy content. The authors also note that “Most processed meals in the typical American diet are higher in carbohydrates and lower in protein than comparable whole food meals.”
Understanding the thermic effect of different foods can help in making food choices at different times in your schedule.
Are Processed Foods Always Worse?
It depends. If your goal is to lose weight, the International Society for Sport Nutrition found that “Meal replacement products (powders, shakes, and bars) have matched or outperformed the effectiveness of whole food-based diets for weight loss and weight loss maintenance.” The studies cited, however, involved research that used carefully controlled diets. Most processed foods outside of a clinical setting (in the “real world”) are typically chosen for their taste and convenience over their protein or nutrient content. Plus, if you have a high training load, you should be fueling to perform at your best and recover effectively and you’ll need high amounts of complex carbohydrates, vitamins and minerals, as well as protein and healthy fats.
Processed foods, like protein powders and protein bars may be useful, however, if your digestive system is in a compromised state either just before or just after training, but always ensure you get nutrients from fruits, vegetables, whole grains, and healthy fats as well once your digestive system has recovered. A post-workout protein smoothie is one example of a more “processed” meal that can help you recover from a tough workout when your digestive system doesn’t feel ready to process a full meal.
If you have difficulty finding foods to suit your training schedule, here are a few pre-workout and post-workout examples to try.
Pre-Workout Meal: 2 hours + before training
Typical Choice 1: Boxed cereal & reduced fat milk
Try instead: Homemade granola and plain Greek yogurt with strawberries & chia seeds
Why: Feel full for longer with more protein, fibre, fat, and minimal processing. A lot of boxed cereals contain high proportions of refined flours and added sugars, undergo high temperature processing methods, and can be low in protein and fibre. Homemade granola can be made with wholegrain rolled oats, a complex carbohydrate high in fibre and can be cooked at a low temperature, with less added sugar and added oil than many store-bought varieties. Adding seeds like chia or hemp increases the fibre, protein, and healthy polyunsaturated fat content. Greek yogurt is higher in protein than reduced-fat milk.
Typical Choice 2: White bread with smooth peanut butter & jam
Try instead: Whole wheat sour dough bread with natural crunchy peanut butter and a banana.
Why: Feel full for longer with more fibre and minimal processing. White bread uses refined white flour which is lower in fibre and can spike blood sugar levels more quickly than whole wheat sourdough bread. Also, the fermentation process of sourdough can actually help reduce blood sugar spikes and keep blood sugar levels more stabilized. Crunchy peanut butter takes more work to digest than smooth peanut butter. Bananas are higher in fibre and lower in sugar compared to jam.
Pre-Workout Meal: 1 hour or less before training
Typical Choice: Eggs on toast
Try instead: Protein bar and/or a banana
Why: You need energy quickly and the high protein/fat combo in eggs will likely take longer to digest than a more processed option like a protein bar. The fruit sugars in a banana will be digested more quickly than the complex carbohydrates in a piece of toast.
Post-Workout Meal: 1 hour or less after training
Typical Choice: 1 chicken breast, 2 cups roasted sweet potato, and 2 cups steamed broccoli.
Try Instead: A protein smoothie with 1 scoop protein powder, ¼ cup quick oats, 1 cup berries, 2 tbsp flaxseed, 1 handful of leafy greens, and 1 cup of your choice of dairy or non-dairy milk.
Why: Many of us just can’t stomach a regular meal immediately after a hard workout. A lightly processed option, like a protein smoothie loaded with wholegrains, veggies, fruits, and nuts/seeds can decrease the workload for the digestive system and help jumpstart the recovery process. The less-processed, whole food option of chicken, sweet potato and broccoli is great for later, 2+ hours after working out.
Wild Cards for Blood Sugar Stability: Sleep and Stress
Sometimes our hunger levels feel like they make no sense: “Didn’t I just eat an hour ago?” you may ask yourself. If you’ve already considered whether you’re getting enough complex carbohydrates, fibre, fat, protein, as well as overall calories, you may need to think about your sleep and stress levels.
Sleep and fluctuating stress hormones are the wild cards in our understanding of fueling for performance and recovery. Not getting enough sleep can impact the body’s ability to regulate blood sugar levels. Sympathetic nervous system activation can alter your blood sugar levels as a result of the flight or fight response. Consider how you can get more sleep and reduce your stress levels by introducing mindfulness practices or other self-care routines into your day. Sometimes, this may also involve introducing a full week of active recovery if your training load has been consistently high for weeks on end.
Julia Howard, MPH, RHN is a distance runner, Registered Holistic Nutritionist, and Run Coach at JKConditioning, a fitness company in St. John’s, Newfoundland, Canada.