Is it better to cut carbs or fat?

Is it better to cut carbs or fat for weight loss? This is one of the biggest questions people ask when they start a diet, and the answer might surprise you. Both work. When calories and protein are matched, low carb and low fat diets produce almost identical fat loss results over the long term. The real winner is the approach you can actually stick with.

That said, each method has different effects on your body, your hunger, your energy, and your health markers. So the smarter question is not “which diet is best” but “which diet fits my life?” Let’s break down what the science says so you can make that call for yourself.

What does the research say about low carb vs low fat?

Multiple large meta analyses have compared low carb and low fat diets head to head, and the findings are very consistent.

A 2022 meta analysis published in Frontiers in Nutrition looked at data across dozens of trials and found that both diets were equally effective for long term weight loss when total calories were the same. A 2020 meta analysis of 38 studies and 6,499 adults found that low carb diets did show a slight edge at 6 to 12 months, with about 1.3 kg more weight loss on average. But over time, that gap shrank.

A 2006 study published in JAMA followed 447 people and found low carb dieters lost 3.3 kg more than low fat dieters at 6 months. But by 12 months, the difference dropped to just 1.0 kg and was no longer statistically significant.

A 2024 network meta analysis ranked low carb as the highest performing diet approach with a P score of 0.8994. But even that study noted results vary based on individual factors like how well someone sticks to the plan.

The takeaway is clear. When protein and calories are equal, fat loss is almost the same on both diets. Pick the one that feels easiest to follow.

Do you lose weight faster on low carb?

In the first 1 to 2 weeks, yes. People on low carb diets often drop weight faster at the start. But a big chunk of that early weight loss is water, not fat.

Here’s why. Your body stores carbs as glycogen in your muscles and liver. Every gram of glycogen holds about 3 grams of water. When you cut carbs, your glycogen stores empty out and you lose that water weight fast. It looks great on the scale, but it comes back the moment you eat carbs again.

After the first few weeks, the rate of actual fat loss between low carb and low fat diets evens out. A 2015 meta analysis published in PLOS One found that stricter carb restriction led to about 0.91 kg more weight loss compared to low fat diets over the study period, but the difference was small.

So if you want a quick number on the scale to feel motivated early on, low carb delivers. Just know that the long game is about fat loss, not water loss.

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How does cutting fat help you lose weight?

Fat is the most calorie dense nutrient you eat. It packs 9 calories per gram, while carbs and protein both contain 4 calories per gram. That means a small amount of fat adds up fast.

A ribeye steak cooked in oil and butter can contain over 60 grams of fat. That’s almost 700 calories from fat alone in one meal. Cutting back on high fat foods like cheese, butter, cream, fatty meats, and oils can save you hundreds of calories a day without changing how much food is on your plate.

For health reasons, you don’t want to go below about 35 to 50 grams of fat per day. Your body needs fat to absorb vitamins A, D, E and K, produce hormones, and keep your brain working properly. But most people eat well above that minimum, so there’s room to trim.

A simple swap works well here. Instead of eating ribeye every night, switch to leaner cuts like top sirloin a few times a week. That one change alone can drop your saturated fat intake by 15 grams per meal.

How does cutting carbs help you lose weight?

Cutting carbs works mainly because it makes you eat fewer calories overall, often without thinking about it. Carb heavy foods like bread, pasta, rice, cereal, and sugary snacks are easy to overeat. Removing them forces you to fill your plate with more protein and vegetables, which are harder to overeat.

Low carb diets also tend to reduce insulin levels. Insulin tells your body to store energy. When insulin drops, your body can access stored fat for fuel more easily. This is one reason people on low carb diets report feeling less hungry between meals.

The 2020 meta analysis of 38 studies found that low carb diets improved HDL cholesterol by about 0.05 mmol/L and lowered triglycerides. Those are both good things for heart health. But the same study found that low carb diets raised LDL cholesterol and total cholesterol, which is worth watching.

Low fat diets, on the other hand, tend to improve LDL numbers more. So the “better” choice for health markers depends on what your blood work looks like right now. Talk to your doctor if you have concerns about cholesterol.

Does it matter where your calories come from?

Yes and no. For pure fat loss, total calories matter most. But the source of those calories affects how your body processes them, how full you feel, and how many calories you burn through digestion.

This is where protein stands out. Your body burns a lot of energy just digesting protein. The thermic effect of protein is about 20% to 30%. That means if you eat 100 calories of protein, your body uses 20 to 30 of those calories just to break it down. Compare that to carbs at 5% to 10% and fat at just 0% to 3%.

So 100 calories of chicken breast and 100 calories of butter are not the same in terms of what your body actually absorbs. You net about 70 to 80 calories from the protein and 97 to 100 from the fat.

Studies show that switching from a low protein to a high protein diet raises your daily calorie burn by about 4% to 5%. That adds up to roughly the same as a 10 minute jog every day. Over time, it contributes to about an extra pound of fat loss per month.

This is one reason both low carb and low fat diets work better when protein stays high. Aim for about 1.6 to 2.0 grams of protein per kilogram of body weight per day, or roughly 0.8 grams per pound.

Which diet is easier to stick with long term?

This is the question that actually matters for results. A meta analysis of popular diets found that every diet was equally poor for long term weight loss on average. But when the researchers sorted people by how well they followed their diet, they found a straight line. The better the adherence, the more weight people lost. It didn’t matter which diet they were on.

Six out of every seven people with obesity will lose a significant amount of weight at some point in their lives. The problem is they don’t keep it off. Research shows that happens because people treat a diet as a temporary event instead of a permanent change.

So ask yourself a simple question. Can you do this for the rest of your life?

If you love bread and pasta and the idea of giving them up makes you miserable, low carb will be hard to maintain. If you enjoy meat, cheese, and rich foods, a low fat diet will feel like punishment. Pick the form of restriction that feels the least restrictive to you.

Some people thrive on low carb because they feel less hungry and more focused. Others do better on low fat because they can eat bigger portions of carb rich foods like rice and potatoes. Neither approach is wrong. The wrong diet is the one you quit after three weeks.

What about keto vs a standard low fat diet?

Keto takes low carb to the extreme. A standard keto diet limits carbs to about 20 to 50 grams per day, which is roughly one banana worth. This forces your body into ketosis, a state where it burns fat for fuel instead of glucose.

Keto can produce faster initial weight loss than standard low fat diets, largely because of the water loss from depleted glycogen stores. Some people also report reduced appetite on keto, which can make it easier to eat less.

But keto is hard to maintain. It eliminates most fruits, grains, legumes, and many vegetables. Social eating gets complicated. And if you fall off the plan, the weight comes back quickly because your glycogen and water stores refill.

A 2024 meta analysis looking at adolescents found low carb diets produced 2.81 kg more weight loss and a BMI reduction of 1.13 compared to other diets. But the studies ranged from very low carb (keto) to moderate low carb, so the results don’t apply only to keto.

For most people, a moderate low carb approach (100 to 150 grams of carbs per day) gives most of the benefits of keto without the extreme restriction. You can still eat fruit, some grains, and plenty of vegetables while keeping carbs lower than a typical diet.

What should you eat on a low carb diet?

Here are the foods that form the base of a solid low carb eating plan.

1. Meat and poultry like chicken breast, turkey, lean beef, and pork
2. Fish and seafood like salmon, tuna, prawns, and cod
3. Eggs prepared any way you like
4. Non starchy vegetables like spinach, broccoli, capsicum, zucchini, and cauliflower
5. Nuts and seeds like almonds, walnuts, chia seeds, and flaxseeds
6. Healthy fats like olive oil, avocado, and coconut oil
7. Full fat dairy like cheese, Greek yoghurt, and butter in moderate amounts
8. Berries like strawberries, blueberries, and raspberries in small portions

Foods to reduce or avoid on low carb include white bread, pasta, rice, cereal, sugary drinks, lollies, cakes, and most processed snacks.

What should you eat on a low fat diet?

A low fat diet focuses on high volume, lower calorie foods. Here’s what that looks like.

1. Lean proteins like chicken breast, white fish, turkey mince, and egg whites
2. Complex carbs like oats, brown rice, sweet potato, quinoa, and whole grain bread
3. Fruits like bananas, apples, oranges, and berries
4. Vegetables of all kinds, especially leafy greens
5. Legumes like lentils, chickpeas, black beans, and kidney beans
6. Low fat dairy like skim milk, low fat yoghurt, and cottage cheese
7. Whole grains like pasta, rice, and cereals with minimal added sugar

Foods to reduce on low fat include fried foods, butter, cream, full fat cheese, fatty cuts of meat, coconut oil, and processed baked goods.

How many calories should you cut to lose fat?

Most people lose fat well on a deficit of 300 to 500 calories per day. That comes out to about 0.25 to 0.5 kilograms of fat loss per week, which is a safe and sustainable pace.

You can create that deficit through diet alone, or combine diet with more movement. Walking 7,000 to 12,000 steps per day is one of the easiest ways to bump up your calorie burn without adding intense exercise.

A 30 minute daily walk adds roughly 3,000 steps and burns 100 to 200 extra calories for most people. Do that every day for a month and you could lose close to an extra pound of fat.

To figure out your starting calories, use a free online calorie calculator and plug in your age, weight, height, and activity level. Track your food for 1 to 2 weeks, then adjust based on how the scale moves. If your average weekly weight goes down by about 0.25 to 0.5 kg, you’re in the right zone.

Weigh yourself first thing in the morning after using the bathroom, do it every day, and take the weekly average. Don’t react to daily swings. Your weight can bounce 1 to 3 kg in a single day just from water, food volume, and salt intake.

Does exercise matter for fat loss on either diet?

Exercise burns calories, yes. But its biggest benefit for fat loss is not the calories you burn during a workout. It’s everything else.

Exercise improves your insulin sensitivity, reduces inflammation, and improves almost every health marker even if you don’t lose any weight at all. Over 70% of people who lose weight and keep it off for years exercise regularly. Among those who regain the weight, fewer than 30% exercise regularly.

Exercise also increases your sensitivity to fullness signals. Research shows that active people regulate their appetite much better than sedentary people. A study of Bengali workers in the 1950s found that sedentary workers actually ate more than lightly active and moderately active workers. Once people were active, they naturally matched their food intake to their energy needs.

So whether you go low carb or low fat, add resistance training 2 to 4 times per week and aim for regular daily movement. The combination of diet and exercise produces better results than either one alone.

How much does a typical low carb or low fat diet cost?

Both diets can be done on a budget or get expensive depending on your food choices.

Low carb diets can cost more because they lean heavily on meat, fish, nuts, and avocados. A kilogram of chicken breast costs around $10 to $14 AUD at most supermarkets, while salmon can run $25 to $40 AUD per kilogram.

Low fat diets can be cheaper because they include more affordable staples like rice ($3 to $5 AUD per kg), oats ($4 to $6 AUD per kg), lentils ($3 to $5 AUD per kg), and frozen vegetables ($2 to $4 AUD per bag).

Either way, buying in bulk, choosing frozen produce, and picking cheaper protein sources like eggs ($6 to $8 AUD per dozen), canned tuna ($2 to $3 AUD per can), and chicken thighs instead of breast can keep costs down.

FAQ

Can you cut both carbs and fat at the same time?

You can, but you have to be careful. If you cut both carbs and fat too much, you won’t have enough energy and your diet will feel miserable. The key is to keep protein high and reduce either carbs or fat (or both slightly) until you hit your calorie target. Don’t slash everything at once.

Is low carb bad for your heart?

Not necessarily. Low carb diets tend to improve HDL cholesterol and triglycerides, which are both good for heart health. But they can raise LDL cholesterol in some people. If you have a family history of heart disease or high cholesterol, get your blood work checked regularly and talk to your doctor about which approach fits best.

Will I lose muscle on a low fat diet?

Not if you eat enough protein and do resistance training. Muscle loss during dieting happens because of too few calories, too little protein, or no strength training. It’s not specific to low fat diets. Aim for 1.6 to 2.0 grams of protein per kilogram of body weight and lift weights at least 2 to 3 times per week.

How low should I go with carbs on a low carb diet?

Most people see good results between 50 and 150 grams of carbs per day. Under 50 grams puts you in ketosis territory, which works for some people but is hard to maintain. Between 100 and 150 grams is moderate low carb and still allows fruit, some grains, and plenty of vegetables.

Do I need to count calories on either diet?

You don’t have to, but it helps. Some people lose weight without tracking by simply cutting out certain food groups. But if your weight stalls, tracking for a few weeks can reveal where extra calories are hiding. Food labels can have up to a 20% error, so consistent tracking matters more than perfect accuracy.

Which diet is better for people with diabetes?

Low carb diets can help manage blood sugar because they reduce the amount of glucose entering your bloodstream after meals. A 2009 study found that a fructose heavy diet worsened insulin sensitivity, while research on low carb approaches shows improved blood sugar control. If you have diabetes or prediabetes, talk to your doctor before making big changes to your diet.

How long does it take to see results on either diet?

You should see measurable fat loss within 2 to 4 weeks on either diet if you maintain a consistent calorie deficit. Low carb will show faster results on the scale in week one due to water loss, but actual fat loss speed is similar between both approaches. Give any diet at least 4 to 8 weeks before judging whether it’s working.

Can I switch between low carb and low fat?

Yes. Some people rotate between phases of lower carb eating and lower fat eating based on their energy needs, training schedule, or personal preference. There is no rule that says you must commit to one approach forever. The body adapts to different fuel sources. What matters is that you stay in a calorie deficit for fat loss and keep protein high regardless of which approach you use.

The carbs versus fat debate is closely tied to how celebrities approach weight loss — discover how Kim Kardashian lost her weight and what strategies she used. Many people following strict diets also wonder why they’re skinny but still have a lower belly pooch. A personal trainer in Maribyrnong can help you find the right nutritional balance for lasting results.