By now, you know that calories come from three different types of nutrients – protein, carbohydrates, and fat. We call nutrients that supply calories macronutrients. A healthy diet typically, but not always, has a balanced array of macronutrients. Depending on the diet that’s hot at the moment, a certain macronutrient might fall out of favor.
For example, fat was the macronutrient villain for years, being the dietary component most strongly linked with weight gain – or so they thought. Then, the Atkins movement came along and changed the way we look at fat and carbs. This radical approach limited dietary carbs to only 50 grams daily – and less than that during the induction phase.
How healthy can such a radical approach be, especially when each macronutrient plays a unique role in keeping you healthy and in shape? If you work out, it’s even more important not to shun a particular macronutrient based on what’s hot in the dietary world. Let’s look at each macronutrient and why you need it.
Carbohydrates
Carbohydrates, along with fat, are your body’s main fuel sources. Your body turns to carbohydrates first, in the form of blood glucose and muscle glycogen. If not enough is available, because you’ve been following the latest low-carb diet fad, it uses fat to make energy. That’s not a problem if you’re just sitting around – but what if you’re a hardcore athlete? It depends on the intensity at which you work out. If you’re exercising at a steady, moderate-intensity pace, your body can easily tap into fat as a source of fuel and your performance probably won’t suffer from a lack of carbohydrates.
It’s when you push your body hard, beyond its lactate threshold, that your body cries out for carbs. That’s because you can’t tap into fat stores quickly enough to meet your body’s overwhelming demand for energy. This happens when you do high-intensity interval training or intense weight training. You need carbohydrates, in such a case, to maximize your performance.
Even if you don’t do steady state training, depriving your body of carbohydrates can work against you. If you do long periods of steady state exercise in a carb-deprived state, your body will break down muscle protein to convert the amino acids to glucose. So, one way or another, your body tries to get glucose. A low-carb diet really CAN affect exercise performance. A study carried out at the University of Connecticut showed that athletes who went from a balanced diet to a low carb one experienced an average 8% drop in muscle power and a 6% drop in aerobic performance.
So why are carbs so maligned by low-carb dieter? Certain people, especially those who are genetically predisposed to metabolic issues, have bodies that handle carbohydrates differently. When these unfortunate folks consume too many of the wrong carbs, their pancreas pumps out too much insulin. Over time, the extra insulin circulating in their bloodstream leads to health problems like metabolic syndrome, type 2 diabetes, or heart disease. Their cells become insulin resistant.
The key to avoiding insulin resistance from a lifestyle standpoint is to shun sugar and refined carbohydrates and choose whole food carb sources that are rich in fiber. These include non-starchy vegetables, fruit, and whole grains. Losing weight also helps. Don’t exclude ALL carbohydrates from your diet – learn to distinguish the good from the bad.
What happens once you go low carb? When you drop your carb intake below 75 to 100 grams per day, you deplete your muscle glycogen stores. Your body then taps into fat and turns fat into ketone bodies to fuel your brain. While you can live this way and may even lose weight but it’s not ideal if you work out at a high intensity.
Fats
At one time, fat was a scary word. Fatphobia isn’t dead but it’s dying. That’s because more people realize that fat is an essential macronutrient and the obesity epidemic didn’t stall when low-fat foods were popular.
The reality is you must have a certain amount of fat in your diet to supply your cells with two essential fatty acids your body must have but can’t make – linoleic and linolenic acid. In fact, between 20- to 30% of your diet should be composed of fat. You need fat to reduce heat loss – who wants to be cold? You also need it for healthy cell membranes and to help you absorb fat-soluble nutrients from the food you eat.
Just as importantly, in terms of exercise, you need fat to build hormones, the chemical messengers that regulate a variety of functions including:
. Reproduction
. Mood
. Energy metabolism
. Muscle growth
Women who eat a very low-fat diet run the risk of losing their periods and fertility. That’s because lack of fat alters hormones that are necessary for conception. When you shun fat, you can enter a menopause-like state with loss of bone mass if you drop your fat intake drastically. Don’t be afraid of fat. The best sources are long-chain omega-3 fat from wild-caught, fatty fish and monounsaturated fats from sources like avocadoes, olive oil, and some nuts, particularly walnuts.
Protein
Amino acids link together to make proteins that serve a useful function in your body. You need protein and its constituent amino acids to repair muscles and tissues and cells as well. Some of the hormones you need for muscle building and general health are also protein in nature. In addition, all the enzymes that cells need to make chemical reactions run are protein.
As a fuel source, protein is more of back-up source than a primary fuel. Your body uses only a small percentage of protein as fuel under normal circumstances. However, when you reduce your calorie and carb intake and expend lots of energy working out, your body turns to protein to fuel exercise. This can lead to loss of muscle tissue. That’s why a balance of macronutrients is best.
Protein’s primary role is to build and repair. If you exercise, either resistance or endurance training, your protein needs are greater because your muscles need amino acids to repair. The recommended 0.8 grams of protein per kilogram of body weight is usually enough to keep the average person in nitrogen balance but isn’t sufficient if you train regularly. In this case, you need more – between 1.2 and 1.6 grams of protein per kilogram of bodyweight. The more training you do, the more your protein needs shift to the higher end of the range.
The Bottom Line
The take-home message? Each macronutrient – carbohydrates, fats, and carbs – plays a unique role in health and fitness. Aim for a balanced diet – high-fiber carbs, healthy fats, and lean protein. Don’t be tempted to jump on the latest weight loss trend that limits one macronutrient. If you’re choosing the RIGHT carbs, fats, and protein, you have nothing to worry about.
References:
On Fitness March/April 2010. “Fueling Your Muscles to Burn Fat”
McKinley Health Center. “What Are Macronutrients?
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An Unexpected Perk of Eating a High-Protein Diet for Weight Loss
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Can You Consume Too Much Protein?
Can Consuming Protein after a Workout Help You Build More Muscle?
Is Protein an Anti-Aging Nutrient?
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