How to Use Carbs to Burn More Fat

Co-authored by Pouya Shafipour, MD, MS and Jennifer Mueller, JD

Last Updated: May 25, 2021 References

With all the low-carb and no-carb diets out there, it's easy to believe that carbs are the enemy if you want to lose weight. However, healthy carbs provide your body with energy to exercise and help keep your metabolism up. The internet is full of conflicting advice on fat burning, but we’ve found that carb-cycling, the practice of cycling higher-carb and low-carb days, is one of the most promising ways to train your body to burn fat for fuel, rather than carbs and muscle. First, find your metabolic rate, so that you know how many calories you need to consume to lose weight. Then, create your carb cycling diet based on your calculations. Don’t forget to choose healthy carb sources! ^{[1]
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Part 1

Part 1 of 3:

Finding Your Metabolic Rate

1
Determine your body mass index (BMI). Your BMI estimates the percentage of body fat you have from the ratio of your weight to your height. Multiple your body height in inches by itself, divide your weight in pounds by that amount; then multiply that number by 703 to get your BMI.^{[2]
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- ${\text{BMI}}={\frac {\text{weight in pounds}}{({\text{height in inches}})({\text{height in inches}})}}$
- For example, consider a 30-year-old woman who is 5'6 (66 inches) tall and weighs 170 pounds, you could find her BMI using the following calculation: (170/(66 x 66)) x 703. The result of the calculation tells you that her BMI is 27.4.
- A BMI over 30 is considered obese. Normal for middle-aged women is between 18.5 and 24.9, so the woman in the example is overweight.
2
Calculate your basal metabolic rate (BMR). The amount of calories your body burns each day simply by existing and carrying out basic bodily functions is your BMR. Even if you're dieting, you must consume at least this many calories or your body won't function normally.^{[3]
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- You can calculate your own BMR using the Harris-Benedict equation. There are slightly different equations for males and females. Use pounds for weight, inches for height, and years for age.
- If you are a biological female, use the equation $655+(4.35)({\text{weight}})+(4.7)({\text{height}})-(4.7)({\text{age}})={\text{BMR}}$ .
- If you are a biological male, use the equation $66+(6.23)({\text{weight}})+(12.7)({\text{height}})-(6.8)({\text{age}})={\text{BMR}}$ .
- If you don't feel like doing that much math, you can find calculators online that will do the work for you if you input your information.
- This estimate will get close to your true BMR, but it is only an estimate. To get your true BMR, you would need to be tested and evaluated by a medical professional.
3
Figure out your total daily energy expenditure (TDEE). Your TDEE includes your BMR plus all the other calories you burn as you go through your day. You can find calculators online that will estimate your TDEE for you.^{[4]
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- Keep in mind it's going to be difficult to come up with a really reliable estimate of your TDEE, but you can get close enough if you're honest about your activity level during the day.
- Online calculators typically ask for a general characterization of how active you are, such as sedentary, moderately active, or intensely active, and the percentage of hours in the day you engage in that activity.
- For example, maybe you have a sedentary desk job five days a week (eight hours sedentary activity each day). On work days, you go for walks in the morning and evening (one hour a day of moderate activity). However, on weekends, you have several hours of intense activity.
- It can be helpful to plug in different numbers to get a range, rather than just finding one TDEE.
4
Keep a nutritional diary. A nutritional diary will help you figure out how many calories you consume on a daily basis. You need to understand this so you can figure out how many calories you need to consume to lose weight.^{[5]
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- It's important to be honest. You might be tempted not to include a piece of candy or another unhealthy snack, but keep in mind that your nutritional diary won't be helpful to you if it isn't accurate.
- Check nutritional labels on packaged foods so you can find the number of calories in the food you've eaten. Be sure to accurately measure portions.
- You can search online to find the caloric content for fresh fruits, vegetables, and other foods you eat that aren't pre-packaged or don't come with nutritional labels.
5
Compare your TDEE to the calories you consume. If you want to lose weight, you need to consume fewer calories than your TDEE. If you consume more calories than your TDEE, generally speaking, you'll end up gaining weight.^{[6]
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- When you're making this comparison, keep your BMR in mind. You have to consume at least that many calories, or your body will lower your metabolism so it can continue to function.
- A carb-cycling diet gives your body more energy through carbs on days when you burn more calories, so you have fuel for those activities. On low-carb days, your body will burn fat for fuel instead of carbs.^{[7]
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6
Calculate your target caloric intake level. To plan your carb-cycling diet, you'll need to set a target number of calories to consume each week, then figure out the amounts of carbohydrates to consume both on high-carb and on low-carb days.
- If you must consume 15,400 calories a week to maintain your current body weight, you need to eat 11,900 calories per week to lose one pound of fat.
- Make your calculations weekly so that you can distribute calories on a daily basis. On your high-carb days, you may need to consume slightly more calories than on your low-carb days.
- Keep in mind that you'll have to adjust these numbers periodically as you start to lose weight and your metabolism changes, or if your activity level changes.
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Part 2

Part 2 of 3:

Building Your Carb-Cycling Diet

1
Start with your highest carb day. On your higher-carb days, you should eat at least 1 to 1.5 grams (0.035 to 0.053 oz) of carbs for each pound of body weight. Once you know what the highest amount of carbs you will eat will be, you can create a cycle around that day.
- For example, if you have calculated you need to consume 200 grams (7.1 oz) of carbs on your highest carb day, than on your lowest carb day you would consume 50 grams (1.8 oz) of carbs.
- You'll need at least one more high carb day, although it doesn't have to be as high as your highest day. It could be, for example, 150 grams (5.3 oz) instead of 200 grams.
- Your high-carb days should fall on days when you engage in the most intense exercise. For example, if you are mostly sedentary during the week but heavily active on weekends, put your two high-carb days on the weekends when you're most active.
2
Work in three low-carb days. All three of your low-carb days don't have to include consumption of the same amount of carbs. Part of cycling means adjusting the amount of carbs you consume each day, but your lowest carb day should be about a quarter of the amount of carbs you consume on your highest carb days.
- Again, calculate the lowest carb day first, and then build your cycle around it. If you are consuming 50 grams of carbs on your lowest day, on the other two days you might consume 100 grams (3.5 oz) and then 125 grams.
- Try to plan your low-carb days for days when you're not as active, keeping in mind that as the cycle rolls around you're going to have to make adjustments here and there. If you want to make a full seven-day cycle, the extra two days should be lower carb days, but closer to the mid-range than to your lowest day.
3
Cycle dietary fat as well. You should significantly decrease your fat intake on your high-carb days to make room for the carbohydrate consumption without having to increase your caloric content.
- You will be consuming more calories on high-carb days than on low-carb days, but you don't want to increase them too much. Keep your weekly caloric target in mind.
- It's okay to eat more dietary fat on low-carb days, just make sure you're eating clean, healthy fats from whole foods. Foods with healthy fats include fatty fish, walnuts, and flaxseed.^{[8]
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  Pouya Shafipour, MD, MS
  Board Certified Family Medicine Specialist
  
  Expert Interview. 8 May 2020.}
4
Avoid carbs at night. When you consume carbs is just as important as the amount and types of carbs you consume if you want to use carbs to burn more fat. The worst time to consume carbs is in the evening, when they are most likely to be turned into fat.^{[9]
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Expert Source

Pouya Shafipour, MD, MS
Board Certified Family Medicine Specialist

Expert Interview. 8 May 2020.}
- If you need a snack at night, eat something high in protein and low in fat, such as a handful of almonds. Avoid sugar and junk food at all costs when you're on a diet.
- Carbs, on the other hand, ideally should be consumed early in the day, such as at breakfast or lunch. Or you could have a carb snack 20 to 30 minutes before you exercise or engage in physical activity.
5
Adjust your diet as needed. Keep your food diary while you're dieting just as you did before you started carb cycling. Use your diary to make notes about your body's reaction to certain types of carb sources and how your body reacts to carb cycling generally.
- For example, you may want to note how your body feels differently on high-carb days than on low-carb days.
- Monitor your weight so that you can adjust the figures and recalculate the amount of carbs you need as you start to lose weight. Under no circumstances do you want to be eating more than 1 to 1.5 grams (0.035 to 0.053 oz) of carbs per pound of body weight, or you will plateau or start to gain weight again.
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Part 3

Part 3 of 3:

Choosing the Right Carb Sources

1
Try to avoid fructose. When you're carb-cycling, try to stick to non-fructose sources of carbs. In other words, try to avoid fruit and fruit sugars. Fructose is more likely to be stored as fat, leading to weight gain or a plateau, regardless of how few calories you're consuming.^{[10]
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- If you're consuming any simple sugars – most typically in powdered form in a protein shake – do it either immediately before or immediately after you work out, so it will be absorbed by your body and used as fuel rather than stored as fat.
2
Eat complex carbohydrates. When you think of simple carbohydrates, think of sugars. Sugar is digested quickly by your body for a short burst of energy, but will not sustain you over the long-term. Complex carbs provide you the energy you need and are less likely to be stored as fat.^{[11]
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- Good sources of complex carbohydrates include brown rice, oatmeal, grits, baked potatoes, sweet potatoes, or yams.
- Check online for carbohydrate content of these foods, as well as proper portion sizes. One good source for this is choosemyplate.gov, a website run by the U.S. Food and Drug Administration.
3
Get your carbohydrates from clean, whole food sources.^{[12]
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Expert Source

Pouya Shafipour, MD, MS
Board Certified Family Medicine Specialist

Expert Interview. 8 May 2020.} Clean sources of carbohydrates are those foods that are low in fat and combine complex carbs with protein. The closer you get to the whole food, the healthier your meals will be.^{[13]
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- Examples of clean, whole food sources include potatoes, yams, brown rice, and oatmeal. When buying these foods, try to buy fresh rather than processed or packaged.
- Stick to the outer perimeter of the grocery store when shopping for your foods, and buy whole grains in bulk.
4
Avoid bread when dieting. Bread is one of the worst carb sources you can consume while dieting. Avoiding bread of any kind (including oat or gluten-free bread) will enable you to burn more fat.
- Your body is motivated to store the calories you get from bread as fat. For this reason, eating bread won't help fulfill your weight loss goals.
- Instead of bread, try baked potatoes, brown rice, or oatmeal, which are all good sources of clean carbs.
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Tips

If you want carb-cycling to work, forget about the concept of a "cheat day." If you want an occasional bowl of sugary cereal or a bagel, work it into one of your high-carb days.

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Warnings

Talk to your doctor before you start this or any diet or weight loss regimen. They can advise you on whether the diet will work to achieve your goals and help you understand any challenges you may have.^{[14]
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Pouya Shafipour, MD, MS
Board Certified Family Medicine Specialist

Expert Interview. 8 May 2020.}

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You may experience some water-weight gain, especially when you first start a carb-cycling regimen. If this is going to be a problem for you psychologically, you may not want to try this diet.

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