Let’s settle the age-old debate on which approach is healthier for you: reducing carbs vs. reducing calories.
Most people want to lose a little bit of weight.
Achieving a healthy weight has many great health benefits! After all, people who are at a healthy weight can expect to control blood sugars better, lower diabetes risk, improve heart health, and reduce the risk for stroke. Plus, people generally report feeling better.
The interest in weight loss has only increased over the last couple of decades, driven in part driven by the food industry, marketing of health claims, and a plethora of addictive foods that are part of SAD (Standard American Diet). Our population’s health has deteriorated while companies and marketing have profited.
The popularity of weight loss programs started with the Atkins diet, Jenny Craig, and Nutrisystem several decades ago. Today, we see popular diets like the keto diet, paleo diet, intermittent fasting, and Whole30.
So, what’s the best approach out there to achieve a healthy weight? How do we get started?
The information out there is confusing and it’s hard to differentiate between truths and myths. Plus, there are many new diets every year that other people swear by. It seems that diet companies are always looking to sell you something that’s actually unhealth.
In this article, I’ll first talk about what a healthy weight means and then compare two common approaches to weight loss: cutting calories vs. cutting carbohydrates (carbs).
So, What’s A Healthy Weight?
The body mass index (BMI) is a helpful measure and textbook definition of a healthy weight. Most healthcare professionals use this to measure your weight — check it out next time you visit your doctor. Your BMI is your weight in kilograms, divided by height in meters squared. Then, it’s rounded to the nearest one decimal place.
To calculate your BMI, you can check out one of these calculators instead of doing the math:
- NIH: Calculate Your BMI – Standard BMI Calculator (nih.gov)
- CDC: Adult BMI Calculator | Healthy Weight, Nutrition, and Physical Activity | CDC
- American Cancer Society: Body Mass Index (BMI) Calculator (cancer.org)
The BMI thresholds are:
- Underweight: Below 18.5
- Normal: 18.5 to 24.9
- Overweight: 25-29.9
- Obese: 30 and higher
However, BMI is not the only measurement when it comes to being healthy. Healthy bodies come in all shapes and sizes. Ultimately, your BMI is intended to be a guide to help double-click into any other potential chronic health issues you may face.
BMI Doesn’t Always Define A Healthy Weight
There are other factors that contribute to the risk for metabolic syndrome and other health risks that we need to take into account. These factors include:
- Body fat percentage
- Waist circumference
For example, someone with a low body fat percentage who regularly works out may have a lot more lean body mass than someone who doesn’t. Since muscle weighs more than fat, I do see a lot of male clients who are classified as overweight or obese based on BMI.
Where your weight is distributed is an important factor to consider here, too. High waist circumference (greater than 35 inches for men or 40 inches for men) contributes to the risk for many chronic diseases. If your weight is distributed in other areas, you may be at lower risk for chronic diseases. I hear this from many folks who consider themselves ‘big-boned’ but don’t consider themselves overweight or obese.
Additionally, as we get older, we tend to lose muscle mass. For older persons who lost weight, the BMI may indicate that these people are underweight when in fact, they are healthy.
Let’s now discuss calories and the pros and cons of losing weight by cutting calories.
What Are Calories?
First, let’s start with the basics and understand what calories are.
Calories are units of energy. In your body, three primary macronutrients contribute to calories in your diet — carbs, protein, and fat. Also, alcohol contributes calories, but it’s not an essential macronutrient.
So, how many calories do you need in your diet? Well, it depends.
First off, everyone has a different basal metabolic rate (BMR), which is what your body uses at rest to keep vital bodily functions going. Your basic functions’ energy needs make up over 60% of your daily energy expenditure! People need calories for even simple actions like sitting or standing use up energy.
Additionally, your individual calorie requirements depend on your age, activity level, weight, height, and sex. For example, this is why a shorter and sedentary female may only need 1,300 calories, whereas a taller and active male may need over 2,500 calories.
Think of food as fuel to provide you with energy (calories) for the day. You would need gas in your car to drive anywhere. Similarly, you’ll need calories for your body to function properly.
Cutting Calories for Weight Loss
The most common approach that you’ll hear is that a calorie is a calorie. To lose weight, you have to reduce your calorie intake. To gain weight, you have to increase your calorie intake.
This is a pretty simple way to keep track of the foods that you eat, of course.
To lose weight, you would need to create a calorie deficit.
Calorie Deficit = Calories Consumed – Calories Used
This equation means that you use more calories than you take in. So, the number should be negative to create a deficit.
You can reduce your calorie intake and create a deficit by eating less, moving more, or a combination of both.
Here’s how the numbers work based on the calorie deficit equation:
- To lose 0.5 pounds per week, you need to reduce your weekly calories by 1,750 (average 250 fewer calories per day)
- Or, to lose 1 pound per week, you need to reduce your weekly calories by 3,500 (average 500 fewer calories per day)
- To lose 1.5 pounds per week, you need to reduce your weekly calories by 5,250 (average 750 fewer calories per day)
- For a more aggressive goal to lose 2 pounds per week, you need to reduce your weekly calories by 7,000 (average 1,000 fewer calories per day)
Are All Calories the Same?
Technically speaking, yes. Calories are units of energy, so a calorie from a carb is the same as a calorie from fat. So, even if you ate 5,000 pounds of healthy food, like carrots, you’d still gain weight!
However, what differs is how your body metabolizes carbs, protein, and fat. Metabolism explains why a high-carb diet is different from a high-fat diet, for example.
Carbs are the primary fuel source for your body and provide 4 calories per gram. Your body is eager to digest sugar molecules and use them for energy (glucose). However, your liver does store some glucose in case your blood sugars fall lower than they should. Your brain especially needs energy from carbs.
A secondary source of energy is fat when carbs aren’t available. Each gram of fat contributes 9 calories. For fats that aren’t needed right away, your body stores them away into fat cells. On the other hand, if you eat a very low-carb, high-fat diet, your body converts fats from food into ketones in your body to then use as energy. Your body can also pull from stored fat to use as energy when needed.
Another source of energy is protein, which provides 4 calories per gram. When consumed, protein is broken down into smaller pieces called amino acids. Protein can also be used for energy when there isn’t enough glucose or fat. If you’re not getting enough protein from food or getting enough carbs or fat, eventually your body will break down muscle to use as energy units.
As you see here, all of these macronutrients provide calories in your diet, but they’re metabolized differently.
Now, let’s look at the pros and cons of cutting calories and the evidence to support both sides of the argument.
Pros of Cutting Calories
One of the benefits of cutting calories is that it’s so easy to get started. You can work with your doctor or a Registered Dietitian to count how many calories you currently eat. Then, you set a goal for how much weight you’d like to lose. And, voila — you have your calorie goal for the week to create a calorie deficit. Calories are also easy to find on packaged foods and menus at restaurants.
Having a simple goal daily is easy for people to track, compared to looking at everything on the label — protein, carbs, fat, etc.
Perhaps the best benefit of reducing calorie intake is that it’s effective. In a medically supervised setting, patients with diabetes or pre-diabetes were prescribed a very low calorie (500-800 calories) or low calorie (800-1200 calories) diet. All participants lost weight over a period of 12 months. 
We also know that losing weight has its many benefits. You can expect better heart health, blood sugar control, lower blood pressure, etc.
Also, cutting back on calories from food, with or without exercise, may decrease inflammation and risk for cancer.  This result was found in a study with post-menopausal overweight women, although more research is needed to understand this link.
Cons of Cutting Calories
As with any weight loss approach, reducing calories has its flaws.
First, you’ll probably see a plateau. Weight loss is not a linear journey, so even if you start out consistently losing weight, it’ll slow down over time as your metabolism adjusts to a new resting metabolic rate (RMR).
This is something that many of my clients struggle with, especially if they’re already eating few calories and don’t want to go any lower (but still want to lose weight).
Second, you may be hungry. Reducing calories increases hunger and stress hormones in your body, known as ghrelin and cortisol.  This is why we commonly see binge eating followed by a period of severe restriction! And, it’s likely why it’s so easy to gain the weight back so quickly after losing it.
Third, you may still consume foods that aren’t healthy for you as long as you stay under your calorie target. It’s an extreme example, but you could technically eat milk chocolate and fries all day and stay under a calorie goal.
A Registered Dietitian’s Perspective
From my perspective, quick weight loss through calorie deficit is not sustainable. For clients who I work with, I don’t recommend trying to lose more than 0.5 to 1 pound per week. Clients who are starting out at much higher weights (over 300-400 pounds, for example) can try to lose a little bit more.
I do like that reducing calories is the easiest way to track what you eat. For people who have never counted anything before like portion sizes or looking at nutrition labels, looking up calories is much easier to learn. We start by breaking down the nutrition label and identifying where calories can be found.
One tricky element of counting calories is making sure that serving sizes are counted correctly. For example, a serving size of ice cream is only ½ cup. Most bowls and cones of ice cream consist of much more than that — they’re generally more like 2 cups total, which is 4 servings!
Another element of reducing calories that I hate is the potential for people to develop eating disorders. When you start identifying a successful day as one where you’ve eaten the fewest calories and weighed in at your lowest, you’re spiraling down a dangerous path.
It’s important to establish a healthy relationship with food and eat foods that nourish and fuel your body. And, if you’re looking to shed a couple of pounds for health and not just vanity reasons, slowly reducing calories is a great way to do so.
How to Reduce Calories
- Read the nutrition label. You can find the calories for any packaged food at the top of the label in bold. For foods that don’t have nutrition labels, you can check websites like MyFitnessPal | MyFitnessPal.com, Food Calculator: Carbs, Calories, Fat, Protein and More (webmd.com), or Food Nutritional Database | CalorieKing.
- Learn how to identify portion sizes. I call this trick ‘talk to the hand’. 1 cup is about the size of your fist. 3 ounces is about the size of your palm. And, 1 ounce is about the size of your thumb. These are general guidelines, of course, but can help you stay on track if you don’t know your exact portion sizes!
- Look up menus before dining out or getting fast food. You can find these directly on a restaurant’s website under the nutrition information section. MyFitnessPal | MyFitnessPal.com, Food Calculator: Carbs, Calories, Fat, Protein and More (webmd.com), or Food Nutritional Database | CalorieKing also have some nutrition information from restaurants and fast-food offerings, as well.
- Try to cook as many meals at home as you can. Foods outside of the home tend to be higher in calories! You can save calories and a couple of dollars by preparing more foods at home. If you can’t avoid dining out altogether, try to eat a snack before you leave the house so that you’re full before you walk into a restaurant.
- Keep track of what you eat. A food journal or diary can help you monitor your calorie intake.
Now, let’s discuss carbs and the pros and cons of cutting carbs.
What Are Carbs?
Each gram of carbohydrate contributes four (4) calories.
Carbs are the primary energy source for your body. When you eat carbs, your body converts them into blood sugars. Then, you use blood sugars as energy.
There are different components that are considered carbs:
- Dietary fiber
- Sugar alcohols and sweeteners
Starch comes from starchy vegetables, legumes, beans, lentils, and grains. They’re your typical carbs.
Sugar is both naturally occurring and added to foods. For example, foods like bananas or milk consist of natural sugars that exist in the foods themselves. On the other hand, foods like donuts, cookies, and soda have sugars that are separately added to make them taste sweet. Sugar also comes in many names and forms, including high fructose corn syrup, cane sugar, honey, molasses, corn syrup, and more.
Then, there’s dietary fiber, which helps you feel fuller after meals and curbs hunger.  There are two types of dietary fiber: soluble and insoluble. Soluble fiber absorbs water — an example of a food high in soluble fiber is oatmeal. And, insoluble fiber passes through your body — an example of a food high in insoluble fiber is celery.
Last but not least, we have sugar alcohols and sweeteners. These are listed on the nutrition label under carbs because they act and taste like sugar. However, your body doesn’t digest or use them in the same way, so the overall calorie contribution may look different than normal carbs.
Cutting Carbs for Weight Loss
Low-carb diets have a long history of efficacy.
Decades ago, the Atkins diet brought the low-carb craze to the spotlight because people were seeing quick results. Most of these diets were based on a low-calorie and low-carb restriction.
Although we love pizza, donuts, and beer, high-carb foods often contribute to weight gain and chronic health conditions over time.
That’s why diets like the keto diet have become so popular today — the keto diet is high in fat, low in carbs, and moderate in protein.
Let’s look at the pros and cons of cutting carbs and the evidence to support both sides of the argument.
Pros of Cutting Carbs
Losing weight by reducing carbs? Yes, it’s possible.
Research now shows that you may be able to lose weight by cutting carbs and replacing them with fat, at least in the short term.  This study suggests that people who had followed a higher-fat and lower-carb diet burned more calories and increase metabolism compared to people with a higher-carb diet. And, the study was co-authored by nutrition expert and renowned professor David Ludwig of Harvard T.H. Chan School of Public Health.
Most carb intake comes from added sugar, and we could all do with fewer added sugars. In fact, the Dietary Guidelines for Americans recommend keeping added sugar calories to less than 10 percent of total calories per day.  If you eat lots of refined carbs like donuts, cookies, and brownies, your blood sugars will rise quickly along with insulin to help bring blood sugar down. This contributes to insulin resistance over time, which is a factor for type 2 diabetes as well as obesity. This is why losing weight by cutting back specifically on refined carbs and added sugars is a great approach.
If you live with diabetes or are at risk for developing diabetes, carb counting is critical. In fact, it’s not just about reducing your carb intake, but getting consistent intake throughout the day. And, to ensure that your blood sugars don’t spike, it’s about getting more complex carbs that will gradually be used for energy. The American Diabetes Association has great resources to get started on carb counting.
Cons of Cutting Carbs
First, you may see weight loss in the short-term when you cut carbs over calories. However, sustained adherence to a low-carb diet is challenging. There is also a lack of data that supports long-term safety and benefit in following a low-carb, high-fat diet.  The short-term success of low-carb diets has helped diets like the keto diet grow in popularity today. You might see some water weight loss, which also contributes to short-term weight loss.
Second, reducing carbs may make you hangry. A study compared mood in people who followed a low-carb, high-fat diet versus a high-carb, low-fat diet. The group who followed a high-carb diet was happier and more focused! This may be attributed to carbs helping with mood and reducing stress in the body. Additionally, the two groups both lost weight, with no significant difference between the two. 
Third, if you eat a diet with less than 40% of calories from carbs, you may contribute to a higher risk for death. However, this is based on some epidemiological studies and meta-analyses and not a randomized clinical trial. 
Last but not least, a low-carb diet may give you constipation. As I’ve discussed above, fiber is considered a carbohydrate. If you’re trying to limit carbs to a very low level, you’ll be skipping out on carbs, too. Since fiber helps you bulk up stool and have more regular bowel movements, without fiber, you’ll experience the opposite effect.
A Registered Dietitian’s Perspective
When it comes to carbs, it’s about quality and quantity.
Regarding the quality of carbs, I like to be selective about what carbs I’m cutting out. Most of the carbs I try to reduce are highly processed refined carbs. I focus on eating complex carbs as much as I can.
However, I truly believe that all foods fit. In the end, it’s about achieving a good balance so that you can enjoy foods while supporting optimal health at the same time. This means choosing mostly whole foods instead of packaged foods, plant-based foods instead of red meats, and fewer sweets overall.
As for the number of carbs, I try to space out when I eat carbs and encourage my clients to do the same. If you eat a lot of carbs in one sitting, chances are higher that your body has to release more insulin to bring the blood sugars down. But, if you space out carbs every couple of hours, you can try to control your blood sugars better and avoid spikes.
For clients who have diabetes, proper training in carb counting is not only helpful but mandatory for best health outcomes. Understanding the carb content in meals and snacks helps ensure that my clients with diabetes can prevent blood sugar spikes and adjust their insulin accordingly after eating.
Overall, it’s important to realize that losing weight by reducing carbs will get you results quickly, but chances are, you’ll gain the weight right back since 1) extreme dieting results in binge eating, and 2) much of the weight loss is from water weight.
Instead, think of ways to improve your long-term health by reducing your intake of refined carbs.
How to Reduce Carbs
- Eliminate or reduce your intake of sweets and refined grains. Simple carbs can cause blood sugar spikes and your body needs to produce more insulin to compensate, whereas complex carbs digest slowly. Look for complex carbs that are lower on the glycemic index.
- Learn the difference between starchy vegetables and non-starchy vegetables. Then, choose more non-starchy vegetables. Even on a low-carb diet, you’ll want to eat non-starchy vegetables that are high in fiber so that you can have regular bowel movements.
- Try to get more calories from other macronutrients, like protein or fat. These other sources will also provide your body with energy. The keto diet has been exceptionally popular as fat is more filling than carbs. If you’re a keto dieter, you can find some healthy keto diet recipes here for inspiration!
- Watch out for hidden carbs. Sugar comes in a variety of names and is not explicitly mentioned in the ingredients list. Common names for sugar include high fructose corn syrup, cane sugar, honey, molasses, and corn syrup. These all consist of sucrose, which is the sugar molecule.
- Keep a log of the carbs that you eat in a day. This will help you identify areas for improvement and keep your intake low.
- Skip the appetizers and sides when dining out. Main entrees at restaurants consist of more protein and veggies, whereas sides are loaded with carbs.
Mental Health Benefits of Healthy Eating & Exercise
With the recent pandemic, more people are reporting anxiety and loneliness.
Fortunately, regular healthy eating and physical activity can help.
In addition to seeing results on the scale or fitting better into your skin, if you establish a regular diet and workout routine, you’ll notice that you’re happier, more energized, and ready to tackle all of life’s challenges!
Plus, there are many ways to establish healthy habits with your family and friends to have extra support along the way.
Weight loss is not just a destination — it’s a journey of learning, education, making some mistakes along the way but learning from them, and most importantly, having fun and feeling better.
The Best Approach?
Rather than pursuing fast weight loss through a restrictive diet just to achieve a certain physique or number of the scale, try to add simple, sustainable changes to your diet and exercise routine.
For best results, this means reducing your calories slightly and specifically cutting back on refined carbs, but not cutting carbs altogether since they’re essential for your body’s functions.
Here are some examples of simple changes you can make today (and sustain over the long-term):
- Cut back on calories from the foods that aren’t as healthy
- Reduce red meat intake
- Eliminate or lessen sweets and refined carbs (e.g. donuts, cookies, brownies) to avoid insulin spikes
- Reduce drinks with added sugars (e.g. fruit juice, mixed drinks, energy drinks, soda)
- Reduce intake of packaged foods
- Aim for gradual calorie reduction from these foods – slow and steady wins the weight-loss race!
- Eat mostly fruits and vegetables
- Consume lean meats, fish, and seafood
- Eat more healthy fats from nuts, seeds, and oils
- Make at least half your grains whole grains
- Go for a 30-minute lunch walk
- Flavor your foods with herbs and spices, not salt
- Drink lots of water
The Bottom Line
In conclusion, there are benefits and consequences to the two approaches: reducing calories or reducing carbs.
Overall, making small, simple, and healthy changes that you’ll be able to stick to within the long-term is the best way to go. It’s about achieving balance and understanding that all foods can fit into a healthy diet. Extreme restriction of either calories or carbs isn’t considered balance in my book.
We’re here to support you, regardless of how you choose to lose weight!
If you’ve tried to lose weight in the past, what’s worked well for you? Comment below and let me know, as I’d love to hear from you!
 Centers for Disease Control and Prevention. Products – Data Briefs – Number 313 – July 2018 (cdc.gov)
 Howarth NC, Saltzman E, Roberts SB. Dietary fiber and weight regulation. Nutr Rev. 2001 May;59(5):129-39.
 Li Z, Tseng CH, Li Q, Deng ML, Wang M, Heber D. Clinical efficacy of a medically supervised outpatient high-protein, low-calorie diet program is equivalent in prediabetic, diabetic and normoglycemic obese patients. Nutr Diabetes. 2014 Feb 10;4(2):e105. doi: 10.1038/nutd.2014.1.
 Imayama I, Ulrich CM, Alfano CM, Wang C, Xiao L, Wener MH, Campbell KL, Duggan C, Foster-Schubert KE, Kong A, Mason CE, Wang CY, Blackburn GL, Bain CE, Thompson HJ, McTiernan A. Effects of a caloric restriction weight loss diet and exercise on inflammatory biomarkers in overweight/obese postmenopausal women: a randomized controlled trial. Cancer Res. 2012 May 1;72(9):2314-26.
 Trexler ET, Smith-Ryan AE, Norton LE. Metabolic adaptation to weight loss: implications for the athlete. J Int Soc Sports Nutr. 2014 Feb 27;11(1):7.
 Ebbeling CB, Feldman HA, Klein GL, Wong JMW, Bielak L, Steltz SK, Luoto PK, Wolfe RR, Wong WW, Ludwig DS. Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial. BMJ. 2018 Nov 14;363:k4583. doi: 10.1136/bmj.k4583. Erratum in: BMJ. 2020 Nov 3;371:m4264.
 Brouns F. Overweight and diabetes prevention: is a low-carbohydrate-high-fat diet recommendable? Eur J Nutr. 2018 Jun;57(4):1301-1312. doi: 10.1007/s00394-018-1636-y. Epub 2018 Mar 14.
 Brinkworth GD, Buckley JD, Noakes M, Clifton PM, Wilson CJ. Long-term effects of a very low-carbohydrate diet and a low-fat diet on mood and cognitive function. Arch Intern Med. 2009 Nov 9;169(20):1873-80.
 Noto H, Goto A, Tsujimoto T, Noda M. Low-carbohydrate diets and all-cause mortality: a systematic review and meta-analysis of observational studies. PLoS One. 2013;8(1):e55030.
 Suter PM. Is alcohol consumption a risk factor for weight gain and obesity? Crit Rev Clin Lab Sci. 2005;42(3):197-227.
 Stanhope KL, Havel PJ. Fructose consumption: considerations for future research on its effects on adipose distribution, lipid metabolism, and insulin sensitivity in humans. J Nutr. 2009 Jun;139(6):1236S-1241S. doi: 10.3945/jn.109.106641. Epub 2009 Apr 29.
 Halkjaer J, Tjønneland A, Thomsen BL, Overvad K, Sørensen TI. Intake of macronutrients as predictors of 5-y changes in waist circumference. Am J Clin Nutr. 2006 Oct;84(4):789-97.