Low Carb vs. Low Fat Diets — Which Is Best for Weight Loss?

Basics of each diet

Although they’re both meant to help you lose weight, low carb and low fat diets are structured differently.

Low carb diet

Low carb dietslimit your intake of carbs to varying degrees. They include ( 1 ):

• Very low carb diets:less than 10% of total daily calories, or 20–50 grams per day on a 2,000-calorie diet
• Low carb diets:less than 26% of total daily calories, or fewer than 130 grams per day on a 2,000-calorie diet
• Moderate carb diets:26–44% of total daily calories

Note that very low carb diets are often ketogenic, meaning that they significantly restrict carb intake to induce ketosis, a metabolic state in which your body uses fat for energy instead of carbs ( 1 ).

Generally, low carb diets restrict foods like sugar-sweetened beverages, baked goods, candies, and sweets. Some versions may also limit healthy carb sources, such as grains, starchy vegetables, high carb fruits, pasta, and legumes.

Simultaneously, you’re meant to up your intake of protein and fat from wholesome sources likefish, meat, eggs, nuts, high fat dairy, unprocessed oils, and non-starchy vegetables.

Low fat diet

Low fat diets involve restricting fat intake to less than 30% of total daily calories ( 2 ).

High fat foods like cooking oils, butter, avocados, nuts, seeds, and full fat dairy are typically limited or banned.

Instead, you’re meant to eat naturallylow fat foodslike fruits, vegetables, whole grains, egg whites, legumes, and skinless poultry. Fat-reduced foods like low fat yogurt, skim milk, and lean cuts of beef and pork are also sometimes permitted.

It’s important to note that some fat-reduced products like yogurt may pack添加糖or artificial sweeteners.

总结

Low carb diets limit foods like grains, pasta, and legumes, whereas low fat diets restrict foods like oils, butter, nuts, seeds, and full fat dairy.

Which is better for your health?

Multiple studies have compared the effects of low carb and low fat diets on weight loss, as well as several other aspects of health.

Weight loss

Most research suggests that low carb diets may be more effective for short-term weight loss than low fat diets ( 3 , 4 ).

According to an older, 6-month study in 132 people with obesity, those who followed a low carb diet lost over 3 times as much weight as those who followed a low fat, calorie-restricted diet (5).

In a small, 12-week study, adolescents with excess weight who followed a low carb diet lost an average of 21.8 pounds (9.9 kg), compared with just 9 pounds (4.1 kg) for those on a low fat diet ( 6 ).

Similarly, a 2-year study gave 322 people with obesity either a low fat, low carb, orMediterranean diet. The low carb group lost 10.4 pounds (4.7 kg), the low fat group 6.4 pounds (2.9 kg), and the Mediterranean group 9.7 pounds (4.4 kg) ( 7 ).

However, other research suggests that low carb and low fat diets may be similarly effective in the long run.

According to a review of 17 studies, participants lost significantly more weight on a low carb diet than on a low fat diet. Although the low carb diet was still more effective after 12 months, the difference between the two slowly decreased over time ( 8 ).

Additionally, a 2-year study in 61 people withdiabetesfound that low carb and low fat diets resulted in similar weight changes ( 9 ).

A large meta-analysis of 48 studies also found that both low fat and low carb diets led to similar weight loss and noted that finding a diet that you can stick to may be the most important factor for successful weight management ( 10 ).

Fat loss

大多数研究表明,低碳水化合物diets are more beneficial for fat loss.

A small, 16-week study found that those who followed a low carb,low calorie dietfor experienced greater reductions in total fat mass and belly fat than those who followed a low fat diet ( 11 ).

A yearlong study in 148 people observed similar findings ( 12 ).

What’s more, several other studies suggest that low carb dietsreduce belly fatto a greater extent than low fat diets ( 4 , 13 , 14 ).

Additionally, one analysis of 14 studies found that low carb diets — and very low carb diets in particular — reduced fat mass in individuals with obesity ( 15 ).

Hunger and appetite

Studies generally show that low carb, high protein dietsdecrease feelings of hungerand improve mood compared with low fat diets, potentially making them easier to maintain long term ( 16 , 17 ).

For instance, one study in 148 people associated a low fat diet with greater reductions in levels of peptide YY — a hormone that reduces appetite and promotes fullness — than a low carb diet ( 18 ).

This may be due to the filling effects of protein and fat. Both of these macronutrients slow the emptying of your stomach to help keep youfeeling fullfor longer ( 19 , 20 ).

Protein and fat have also been shown to affect several hormones that control hunger and appetite.

In a small study, high protein and high fat meals increased levels of the fullness hormone glucagon-like peptide 1 (GLP-1) and decreased levels of ghrelin, a hunger hormone, to a greater extent than a high carb meal ( 21 ).

Blood sugar levels

Low blood sugar levels can increase feelings of hunger and cause serious side effects like shakiness, fatigue, and unintentional changes in weight ( 22 ).

Limiting carb intake is one strategy to helpcontrol blood sugar levels( 23 ).

One study in 56 people with type 2 diabetes determined that a low carb diet was more effective at controlling blood sugar, increasing weight loss, and reducing insulin needs, compared with a low fat diet ( 24 ).

Another small study in 31 people comparing the effects of both diets found that only the low carb diet reduced levels of circulating insulin, which led to increased insulin sensitivity ( 25 ).

Increased insulin sensitivitycan improve your body’s ability to transport sugar from your bloodstream into your cells, resulting in enhanced blood sugar control ( 26 ).

Still, while a 3-month study in 102 people with diabetes revealed a low carb diet to be more effective than a low fat diet for weight loss, there was no significant difference in terms of blood sugar levels ( 27 ).

As such, more research on low carb and low fat diets’ blood sugar effects is needed.

总结

Research suggests that low carb diets are more effective for short-term weight loss than low fat diets, as well as that they may lead to greater reductions in body fat and hunger.

Other effects on health

Low fat and low carb diets may affect other aspects of health in different ways. These include:

• Cholesterol.A review of eight studies found low carb diets to be more effective at improving levels of HDL (good) cholesterol and decreasing triglyceride levels than low fat diets. Neither diet significantly affected LDL (bad)cholesterol( 28 ).
• Blood pressure.Although studies show that both diets can reduce short-term blood pressure levels, research on their long-term effects on blood pressure has been mixed ( 29 , 30 , 31 , 32 ).
• 甘油三酯。Several studies note that a low carb diet can lead to greaterreductions in triglyceridesthan a low fat diet ( 14 , 28 , 33 ).
• Insulin.Studies on low carb and low fat diets’ effects on insulin levels have turned up conflicting results. More research is needed to determine whether one is more beneficial than the other (5, 25 , 34 , 35 ).

总结

Low carb and low fat diets may affect your cholesterol, blood pressure, triglyceride, and insulin levels.

The bottom line

Low fat diets are considered a popularweight lossmethod.

However, low carb diets are linked to greater short-term weight loss, along withincreased fat loss, reduced hunger, and better blood sugar control.

While more studies are needed on the long-term effects of each diet, studies show that low carb diets can be as effective for weight loss as low fat diets — and may offer several additional health benefits.

Whether you choose a low carb or low fat diet, keep in mind that sticking to an eating pattern over the long run is one of the most critical factors for success with both weight loss and overall health ( 36 ).