How many times have you heard a friend, family member or coworker say “I’m going on a low-carb diet”? Chances are, you probably know someone (maybe even you) that has tried this method for weight loss. And why not? The Atkins diet, the Paleo diet, and countless others advise that going low-carb is the key to achieving the body of your dreams. But is this really the answer to healthy, sustainable weight loss? Could it be that carbohydrates get a bad rap not because we don’t need them but because most of us don’t know how to use them to our advantage, which begs the question; carbs: friend or foe?
When food is digested, it leaves the stomach and enters the intestines where it is absorbed into the blood stream in the form of blood glucose, which is then stored in the muscle cells as “glycogen” or fuel for our bodies. This process is known as “gastric emptying time.” Gastric emptying time varies based on what you eat, and when the process is complete your blood glucose levels drop, signaling that it’s time to eat again. Proteins have a gastric emptying time of around 2 hours, while fats take 3-5 hours. Carbohydrates however, take between 20 and 40 minutes. This is why we often feel an energy crash shortly after eating a carb-heavy meal. This is also why carbohydrates have gotten such a bad reputation. However, studies conducted on gastric emptying time have found that when you add a protein in with a carbohydrate, gastric emptying time is slowed considerably (remember; it takes 2 hours for proteins to be digested). This allows for blood glucose levels to rise slowly and drop slowly, releasing steady energy for the body to use effectively and preventing that dreaded energy crash. For this reason, proteins should always be present in a meal that includes carbohydrates. The only time it is acceptable to have carbohydrates alone is immediately after exercising because glycogen synthase levels are high, so the body will take all that glycogen and store it in the cells for later use. If you eat a high-carb meal and then engage in a sedentary activity like sitting at a desk or in front of the TV, the glycogen will instead be stored as fat because the body can’t use it right away. So, instead of swearing off all carbs, we just need to know how to eat them so our bodies can use them properly.
Now that we’ve established that carbohydrates are vital for providing energy to our cells, how do we know how much and what types we should eat? The American College of Sports Medicine recommends that 58% of our diet should consist of carbohydrates, the RDA recommends 130 grams per day, and the Institute of Medicine recommends anywhere from 45-65% or more depending on the individual and their level of activity. Runners, for example, probably need closer to 70%. Why? Carbohydrates are our fuel. They are the body’s greatest source of energy. You wouldn’t get in the car for a cross-country road trip without putting gas in the tank first, right? However, you wouldn’t need as much gas if you were only going for a drive down the road. This is the mentality that one should use when determining how many grams of carbohydrates they should be eating daily. So, how do you know the amount of carbohydrates that is right for you? First of all, you need to know how many total calories you should be taking in daily. It is beneficial to enlist the help of a nutritionist or dietician when determining this, but you can get a good idea using this simple formula:
1. Calculate your BMR (basal metabolic rate). This is the amount of food your body requires just to maintain it’s most basic functions (breathing, digestion, etc.). You can figure this out by taking your weight in kilograms (lbs./2.2) and multiplying it by 1 if you are a male and 0.9 if you are female (this represents the calories burned per kilogram per hour). Multiply that number by 24 (hours in a day) and you have your BMR.
2. Add in your activity factor. If you are sedentary (you do not exercise at all and have a job that requires little to no physical activity), give yourself a 1.1. If you are on your feet at least half of the day, give yourself a 1.2 for light activity. If you are on your feet most of the day, give yourself a 1.3. If your job requires a lot of physical activity (manual labor), give yourself a 1.4.
3. Calculate your daily exercise expenditure, or the amount of calories you burn during exercise per day. This can be a little tricky, which is why it may be helpful to have a nutritionist or dietician assist in getting the most accurate calculation possible. You will need to consider how many days a week you work out and what kinds of workouts you do to get approximate number of calories burned per workout (be careful not to overestimate).
4. Take your BMR and multiply it by your activity factor, then add your daily exercise expenditure. Now you have a good idea of how many calories you should be eating daily.
5. Now, calculate 58% of that number and you have a general idea of how many calories per day need to come from carbohydrates. Carbs have 4 calories per gram, so take that number and divide by 4 to figure out how many grams of carbs that equals.
Now that you have a general idea of how many grams of carbohydrates your body requires to keep you going, it is equally as important to know which kinds of carbohydrates are best. There are two types of carbohydrates; simple and complex. Simple carbohydrates consist of sugars (fruit juices, white breads and pastas, corn syrups, etc.), while complex carbohydrates consist of starches (whole grains, beans, legumes, etc.). You should never eat a food with more than 20% of it’s carbs coming from sugar. In general, this means that we should stick with the complex carbohydrates as they are more filling and slower to digest. While fruit does include sugar and simple carbohydrates, they also have essential vitamins and nutrients that your body needs, so you don’t need to neglect these foods entirely. Just remember to limit your intake and combine your fruit with a protein to keep those blood glucose levels in check.
Carbs don’t need to seem like the enemy; following these simple rules will help you to turn them into a useful tool toward reaching your weight loss goals in a healthy and effective way.