The Low-Carb vs. Low-Fat Diet Debate

Low carb? Low fat? Calorie counting? With each new post on social media, people suggest a new diet to lose weight quickly.

We mostly hear recommendations for low-carb or low-fat diets while always staying aware of total calories.

All of the different advice can be confusing, so here we’ll talk a little about the pros and cons of some popular plans and why overly strict diets rarely work long-term.

Low-Carb Diets

Low carb diets include all of the different plans that involve dramatically cutting carbs.

Just to name a few, this category has included Paleo, Caveman, Atkins, Keto, and South Beach over the years.

Plans vary in their severity of carbohydrate restriction, but all aim to cut carbs and usually focus on the reduction of grains like pasta, bread, cakes, etc.

Other common sources of dietary carbohydrates (that low-carb diets may target) include dairy, fruits, vegetables, beans, and sweets.

If a low-carb diet is properly designed, it should replace some of these carbohydrate-rich foods with vegetables while still including reasonable amounts of lean proteins and healthy fats.

As you cut carbs, it also becomes more and more important to monitor the quality (not just quantity) of your choices.

How Many Carbs

Like most health topics, the more moderate plans are considered safer and more sustainable than their more extreme counterparts.

For example, a diet that suggests cutting carbs to only 1-2 servings per meal is more realistic than one that tells you to eliminate carbs entirely.

In a typical low-carb diet, you may aim for 240 to 520 calories (60-130g) of carbohydrates per day. In contrast, someone on a regular 1800-calorie diet would have closer to 810-1170 calories (203-293g) of carbs per day.

This second number reflects current US dietary guidelines, which suggest 45-65% of daily calories come from carbs. An individual’s diet might actually contain many more carbs if they eat a lot of starchy foods. 

Therefore, a ‘moderate’ low-carb diet already involves eating many fewer carbs.

If you want to calculate how many of your daily calories are coming from carbs, you only need to know how many calories you eat per day and your daily grams of carbohydrates.

There are 4 calories per gram of carbohydrate. So, simply multiply your total grams of carbohydrates times four to find daily calories from carbs.

Then, if you want a percentage, divide that number (total calories from carbs) by the total calories per day. While you can do this calculation manually, many tracker apps are also made to do the math for you.

If you’re on a low-carb diet, you will find this percentage is likely much lower than the typical 45-65%.

Why Cutting Carbs Works

Low-carb diets have some definite benefits. Perhaps the most relevant is their effectiveness in speeding up weight loss.

Many people report greater weight loss with a low carbohydrate diet as compared to their normal diet.

This may be due to several factors.

First, decreasing carbs causes a decrease in insulin. Since carbs (especially simple carbs) lead to spikes in blood sugar, the pancreas produces more insulin when you eat a lot of carbs.

Insulin is the hormone responsible for storing fat. Therefore, less insulin can translate into less fat storage and, ultimately, weight loss.

Also, when people cut carbs, they often (intentionally or unintentionally) cut calories as well.

If all else remains the same, eating less will lead to weight loss. Better yet, cutting carbs usually means eating less junk and processed food and hopefully more fruits and vegetables.

This swap helps build healthier habits and aids in weight loss. Replacing the fiber in grains with fiber from fruits and veggies also reduces the risk of constipation.

If you just suddenly stop eating grains (the main source of carbs and fiber) and don’t replace them with other sources of fiber, constipation can be a common side effect.

Low-carb diets are also beneficial for people with certain medical conditions, like diabetes.

Due to the strong relationship between carbs and insulin production, many doctors recommend that patients with diabetes follow a carbohydrate-controlled diet.

Sometimes this means low carb, while other times, it simply means keeping carb intake more or less constant. Nonetheless, monitoring carbohydrate intake (whether low or normal) is healthy for all of us, not just those with diabetes.

Low Carb Cons

Those that eliminate whole food groups require a severe restriction of total carb intake or only allow certain specific foods are considered extreme.

Each food group provides certain critical nutrients, so elimination increases the risk of vitamin or mineral deficiency.

This ties closely with the risk of ketosis, which can be caused by very severe carbohydrate restriction.

While mild ketosis is a relatively common biological process, if ketone levels rise, it can evolve into ketoacidosis, which is very dangerous.

Staying in ketosis is not maintainable for most people, so it is not generally recommended for weight loss as a sustainable lifestyle change.

Other risks are generally related to poorly designed low-carb diets. For example, if calories from carbs are replaced with more meat and fat instead of vegetables, it can cause problems.

Those with high cholesterol or other conditions that require lower-fat diets should use caution when eliminating carbs.

Without proper guidance, a low-carb diet can easily turn into a high-fat diet (especially high in saturated fat from meats and animal products).

The protein is great, but be conscientious of the fat and calories. If you didn’t buy much meat before, low-carb diets can also mean a big jump in the grocery bill. Keep all of this in mind before committing to a low-carb diet.

Low-Fat Diets

Low-fat diets are less trendy but commonly recommended by doctors.

They were very popular about twenty years ago but have lost some popularity in recent years.

Low-fat diets involve cutting your total fat intake, usually with a special eye toward reducing saturated and trans fats. Popular low-fat diets include the Mayo Clinic Diet, American Heart Association Diet, and TLC.

How Much Fat

The general recommendation is that calories from fat make up no more than 25-30% of daily calories.

This does not mean that fatty foods should represent 25-30% of your daily foods. Fat is the most calorie-dense macronutrient at 9 calories per gram.

As a result, fatty foods are more caloric than their lower-fat competitors and can easily add up.

For those with specific conditions, like high cholesterol or triglycerides, fat should be an even smaller part of your diet (closer to 20%).

The American Heart Association points out the particular importance of tracking saturated and trans fats (“bad” fats). Saturated fats come from animals and should only make up 5-6% of calories for those with high cholesterol.

Trans fats come from processed foods and should be avoided when possible. The goal is for most of your calories from fat to come from “good” unsaturated fats, like those found in fish, walnuts, and olive oil.

Also, keep in mind that our bodies need fat to function.

Just like carbs, low-fat diets aren’t healthy if taken to extremes.

Your body needs a certain level of dietary fat (preferably from healthy sources) to function properly, so aiming for a no-fat diet is not healthy either.

Benefits of a Low-Fat Diet

Low-fat diets are great for overall health because they are a relatively easy way to reduce total calories and prove effective in reducing cholesterol (LDL) and triglycerides.

They are popular as a medically-recommended lifestyle change because low-fat diets allow you to eat foods from all food groups, and the only major requirement is moderate consumption of higher-fat foods.

One of the reasons low-fat diets prove so sustainable is that they closely mirror the recommendations outlined in our dietary guidelines.

MyPlate advocates the inclusion of lean proteins, plenty of fruits and vegetables, and low-fat/non-fat dairy – just like low-fat diets.

There is also significant evidence showing the efficacy of low-fat diets in weight loss and control of blood lipid levels.

Low-Fat Cons

Just like every other plan, low-fat diets have their downsides too.

One major criticism of low-fat diets is that they lead to higher sugar intake. This is for two reasons.

First, it is easy to replace higher-fat foods like meat and cheese with lower-fat/fat-free carbohydrates, which are naturally higher in sugar.

Also, many fat-free products compensate for the lack of fat by adding sugar. Companies do this because if the products are tasteless, nobody would buy them, so they add sugar when they can’t add fat.

Obviously, it’s not great for us to eat too much sugar either.

Some people also say that low-fat and fat-free foods aren’t as filling or as flavorful, so they end up eating more calories while lowering fat intake.

Given the commonality of this concern, it is definitely something to consider before changing your lifestyle to low-fat.

If you’re eating more calories, you won’t lose weight, even if they’re lower-fat calories.

The Beauty of Balance

So, what do we do? There’s no perfect plan. Different diets work differently for different people. Some people swear by a certain diet, while other people say it doesn’t work at all.

Therefore, experts usually recommend portion control and making healthy, balanced choices from each food group:

• Fill half your plate with non-starchy fruits or vegetables
• Choose one serving (about ¼ plate) of whole grains
• Complete your plate with one serving (about ¼ plate) of meat or other protein
• Aim for 3 servings per day of low-fat/fat-free dairy or alternatives
• Limit fat (especially saturated and trans fats) and salt
• Stay hydrated!

MyPlate was created by experts and is endorsed by many more.

Notice that these recommendations include foods from each food group but encourage moderation.

In the end, this allows for significant variation to adjust for specific health concerns (e.g., low fat for someone with high triglycerides or carb-controlled for someone with diabetes) while still maintaining balance.

A qualified professional, including your doctor or registered dietitian, can help you understand which modifications are best for you.

There are also a couple of general rules that can help you avoid less healthy diet plans. Be wary of diets that force you to eliminate an entire food group or any that promise easy success without a long-term commitment.

We get diverse and important nutrients from each food group, so elimination can be risky if not well-planned or supervised by a professional.

Also, ensure the main foods you’ll be eating are easy to find, and affordable, and include foods you enjoy so that you can stick with the plan in the long term!

Do you count calories? Carbs? Fat? Nothing? Everything? Let us know in the comments section below!