The body breaks down most carbohydrates from the foods we eat and converts them to a type of sugar called glucose. Glucose is the main source of fuel for our cells. When the body doesn't need to use the glucose for energy, it stores it in the liver and muscles. This stored form of glucose is made up of many connected glucose molecules and is called glycogen. When the body needs a quick boost of energy or when the body isn't getting glucose from food, glycogen is broken down to release glucose into the bloodstream to be used as fuel for the cells.
Fat is an important component of a diet designed to fuel exercise. One gram of dietary fat equals nine calories, and one pound of stored fat provides approximately 3,600 calories of energy. This calorie density (the highest of all nutrients), along with our seemingly unlimited storage capacity for fat, makes it our largest reserve of energy.
These calories are less accessible to athletes performing quick, intense efforts like sprinting or weight lifting. But fat is essential for longer, slower, lower intensity and endurance exercise, such as cycling and walking.
Everything we eat is made up of macronutrients (protein, carbohydrates, and fat) and micronutrients (vitamins and minerals). These are converted to energy inside the body, helping to fuel all of our bodily functions.
Dietary fat has been blamed for many health problems, but it is actually an essential nutrient for optimal health. Adipose tissue (stored fat) provides cushion and insulation to internal organs, protects nerves, moves certain vitamins (A, D, E, and K) throughout the body, and is the largest reserve of stored energy available for activity.
Stored body fat is different from dietary fat. Body fat is only stored in the body when we consume more calories than we use, from any and all foods we eat, not just from dietary fats. There is an optimal level of body fat for health and for athletic activity.
Fat provides the main fuel source for long-duration, low- to moderate-intensity exercise (think endurance sports, such as marathons). Even during high-intensity exercise, where carbohydrate is the main fuel source, the body needs fat to help access the stored carbohydrate (glycogen). Using fat to fuel exercise, however, is not a simple process. It has three key parts:
- Digestion: Fat is slow to digest and be converted into a usable form of energy. This process can take up to six hours.
- Transportation: After the body breaks down fat, it needs time to transport it to the working muscles before it can be used as energy.
- Conversion: Converting stored body fat into energy takes a great deal of oxygen, which requires decreased exercise intensity.
So athletes need to carefully time when and how much fat they eat. In general, it’s not a great idea to eat foods high in fat immediately before or during intense exercise. First, the workout will be done before the fat is available as usable energy. And second, doing so can cause uncomfortable gastrointestinal symptoms, such as nausea, vomiting, and diarrhea.
Popular low-carbohydrate and high-fat diets, such as the ketogenic diet and Paleo diet, all work on the same premise. The theory is that lower carbohydrate intake, coupled with high fat and moderate to high protein intake, leads to burning body fat as the main fuel source while exercising.
There is, in fact, some scientific evidence that long-term low-carb/high-fat diets are safe and may help improve metabolic risk factors for chronic disease. In studies, these diets have shown to be beneficial for performance in ultra-endurance sports—but at least several months of adaptation to a low-carb/high-fat diet are required for metabolic changes to occur.
If you’re looking to make a change and get healthier, working out is an important step in the right direction. But for overall health, and for weight maintenance or weight loss, what you eat is much more important than how or how often you work out.
Experts often put the impact of food on health at 80 percent, with exercise at 20 percent. So you’ll give yourself a huge boost toward your health goals if you pay attention to what you eat, as well as how you exercise. Here are the basics:
We need all three macronutrients (carbohydrates, proteins and fats) for optimum health.
Carbohydrates are the preferred fuel for most cells in the body. Our main energy source, carbs are important for fueling the body and brain, protecting our muscles and feeding the bacteria in the gut.
- Carbohydrate-rich foods include starchy vegetables (potatoes, sweet potatoes, taro), breads, pasta, rice and other grains, legumes, and dairy.
- Healthier carbohydrates are in whole, unprocessed versions of these foods: veggies and fruit; and whole grains rather than white, processed ones.
Proteins are important “building blocks” for our bodies. Proteins are in every one of our cells, where they’re used to build and repair tissues; to make enzymes and hormones; and to build muscle, bone, cartilage, skin and blood.
- Protein-rich foods include meat, chicken and fish; tofu; eggs; dairy products; nuts; and beans and other legumes.
- Healthier protein foods are the above foods in their most whole, natural forms.
Fats are also necessary for every cell in our bodies. They help us absorb some vitamins (vitamins A, D, E and K) and help regulate hormones. Fats provide energy and build energy reserves, and they protect and insulate our organs.
- Fats are found in meat, fish, chicken and dairy; oils; spreads; and nuts and seeds.
- Healthier fats are olive, avocado and seed oils; nuts; seeds; and some dairy.
We also need some micronutrients from our food. The World Health Organization calls micronutrients “magic wands that enable the body to produce enzymes, hormones and other substances essential for proper growth and development.”
Here are some of the important ones:
- Iron helps transport oxygen throughout the body. If we don’t have enough, we’re likely to have lowered immunity and can become anaemic. Iron is found in red meat (the best source), chicken and fish; grains; vegetables and legumes; nuts; and eggs.
- Vitamin A is important for vision, the immune system, skin and growth in children. Vitamin A is found in liver, oily fish, milk, egg yolk and cheese.
- Iodine is necessary to make thyroid hormones, which control the body’s metabolism and are responsible for bone and brain development during pregnancy and infancy. Iodine is found in fish and seafood; seaweed (e.g., nori and kelp); small quantities in dairy foods, vegetables and meat; and fortified foods such as salt and bread in some countries.
- Vitamin C is essential for keeping gums, teeth and bones healthy; helping wounds heal; helping the body resist infection; helping the body absorb iron; and forming collagen to build bones and blood vessels. Vitamin C is found in colorful fruits and vegetables.
- Calcium is essential to build and maintain bones. It enables the blood to clot and muscles to contract and helps regulate blood pressure. Calcium is found in dairy (the best source), especially milk, cheese and yogurt. It also can be found in fortified nondairy milks, sesame seeds, nuts, prawns, sardines and dark green vegetables.
What are the basics of a good diet?
To get the essential nutrients and micronutrients, we need to eat a wide variety of foods. The composition of a healthy diet can vary; different people need different combinations of foods and in different amounts.
Around the world, there are groups of people who stay healthy and live the longest. Known as the Blue Zones, people in these communities eat very varied diets. But there are some common factors, which are reinforced by scientific evidence. These factors include the following:
- An emphasis on plant-based foods: Eating “mostly plants,” whether we include animal products or not, is clearly associated with good health.
- An emphasis on whole, unprocessed foods: Limiting refined carbohydrates, added sugars and processed foods is important for good health.
Is there an ideal ratio of carbohydrates, protein and fat?
We’re all different, and our needs for different nutrients can really vary. A good basic guide, though, is to consider the “ideal plate” model for every meal. That means:
- Half a plate of colorful, non-starchy vegetables and/or fruit
- A quarter plate of carbohydrates
- A quarter plate of protein
This model can apply to simple meals as well as mixed meals like pasta or stir-fried dishes. People’s ages, activity levels and some health conditions can affect whether we need more or less of a particular nutrient. Seek expert advice from a nutritionist or dietitian if you’re not sure what’s right for you.
How often should I eat?
The traditional “three meals a day’” model is a pattern of eating that fits in with many people’s lifestyles. And breakfast eating is associated with positive health outcomes, including weight management. But overall, the evidence suggests it doesn’t really matter too much when we eat, as long as we get the nutrition we need from the meals and snacks we have in our days and weeks.
How should I eat if I’m working out?
Whether you’re working out, playing sports or going for a run, food can make a difference to how much energy you have and how well you recover from your workout. Remember, though, it’s the food you eat most of the time—your basic, healthy, everyday diet—that’s the most important, not the food you eat before or after a workout.
What should I eat before and after exercise?
If you’re working out first thing in the morning, you may be better off not eating; your body can only use food it’s already digested. After your morning workout, make sure you get a meal containing carbs and protein within two hours.
If you’re working out during the day or the evening, make sure you’ve had a meal with carbs and protein in it three to four hours before your workout or a snack containing protein and carbs an hour or two before your workout. After your workout, make sure you have a meal within two hours.
Try to avoid “rewarding” yourself with extra food or drink after a workout; you could easily undo all your good work with a poorly chosen snack.
What about water?
Hydration is really important for keeping us well during the day, whether we’re exercising or not. We lose water naturally through breathing and sweat; when we exercise, this can happen faster. Make sure you stay hydrated with water as your main drink. Keep an eye on your urine color to tell you how you’re doing. (Pale is good.)
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This piece originally appeared on LesMills.com.
Photo credit: Kimberly Nanney, Unsplash