If you’re looking to make a healthier lifestyle change, you’ve probably heard about low-fat and low-carb diets. Both diets can be effective for weight loss and while they share many similarities and benefits, following the diets themselves can become very different from each other. Both diets have pros and cons of their own, so it's important to consider which type of diet best suits your personal lifestyle and goals.
While both diets eat mostly healthy proteins, fruits, and vegetables, low carbs avoid breads and grains, while low fats avoid nuts and oils.
It’s controversial whether the Keto diet is safe for those with prediabetes or type 2 diabetes due to the insulin that can vary during restriction.
Low-carb and low-fat diets share many of the same benefits, but there are a few differences in that one may be effective, whereas the other has yet to see significant results.
Low-fat diets are often widely advocated by physicians for their health benefits, primarily focusing on those who experience cardiovascular-related issues. However, despite being essential for the body, it is important to consume fats in a limited amount, as high-fat diets can lead to an increased risk of diabetes, heart disease, cancer, metabolic syndrome, and more (including death). It is also essential to note that while many manufacturing companies tout low-fat products, they often replace the fat with large amounts of refined carbohydrates, increasing the risk of metabolic disorders. Some products may also add extra sugars in place of the fat.
Researchers have found that diets rich in carbohydrates and low in unsaturated fat can negatively impact lipoprotein risk factors and increase cardiovascular risks. Recent studies in men have reported that reducing the total amount of fat consumption to 27% and saturated fatty acid intake to 8% of energy, respectively, can result in a substantial decline in both the total and LDL cholesterol levels. While following a low-fat diet, it’s vital that you still consume the unsaturated fats that your body needs. Unsaturated fats (polyunsaturated and monounsaturated) are often found in oils, nuts, seeds, and even some animal sources. Because these foods typically contain a high amount of fat, it might be a good idea to talk to your doctor about the best way to still get in all your nutrients while on a restrictive diet. Some good foods for a low-fat diet include:
- Whole grain cereal
- Egg whites
- Chicken/turkey breast (skinless)
- Low-fat dairy (be careful of high sugar)
There are four classifications of diets based on carb intake:
|Very low-carb diet
|Less than 10% of daily intake comes from carbs (20–50 g/day).
|Between 10–25% of daily intake comes from carbs (less than 130 g/day).
|Carbs comprise 26–44% of daily intake.
|Carbs comprise greater than 45% of daily intake.
On a daily basis, Americans typically consume a massively high-carb diet, ranging from 45 to 65% of their daily intake, exceeding the high-carb limit based on the Dietary Guidelines for Americans.
Low-carb approaches are popular for weight loss. The main idea is that lowering insulin (the hormone that triggers an anabolic, fat-storing state) can improve cardio metabolic function and lead to weight loss. This is usually achieved by increasing the intake of fats and proteins to compensate for the reduction of carbohydrates and give the body enough energy to function correctly. The potential benefits of this approach come from the increased satiety and reduced rebound hypoglycemia associated with increased fat and protein intake, leading to a caloric deficit.
Keto vs low-carb diet
Of the various low-carb approaches, the ketogenic (keto) diet is one of the most popular, but while they are incredibly similar, they have their differences. A low-carb diet limits consumed carbs, specifically simple and refined carbs generally found in sugary foods, pasta, and bread.
On the other hand, the Keto diet vastly restricts carbohydrates down to between 20–50 grams per day (considered very low-carb) while eating a high amount of fat and protein. This forces the body to use the fat stored in adipose tissue instead of glucose for fuel to produce ketones, creating a state of nutritional ketosis.
Some research has shown that low-carb diets have led to improvements in health conditions such as diabetes, polycystic ovary syndrome, acne, neurological diseases, and cancer. They have also showed improvements in respiratory and cardiovascular disease risk factors. Other research points to increased health risks. Epidemiological studies and meta-analyses have shown that some low-carb diets of under 40% were linked to an increased mortality risk.
A list of healthy low-carb foods includes:
- Non-starchy vegetables
- Fruit (avoid high-carb fruit)
- Full-fat dairy
Low-carb vs. low-fat diet: which is better?
Each diet has negative and positive aspects and based on one’s health conditions, you should decide which diet might be best for you.
The most controversial evidence is whether a low-fat diet can reverse type 2 diabetes or lower insulin levels. Researchers at Duke University Medical Center studied the effect on mice and found that they could reverse type 2 diabetes in mice simply by feeding them a very low-fat diet. Extremely low-fat diets like keto, though, don’t allow the body to use insulin properly, causing blood sugar to become erratic and leading to insulin resistance, raising the risk for type 2 diabetes. On the contrary, a low-carb diet can easily improve type 2 diabetes.
Both low-carb and low-fat diets can lower cholesterol levels and the risk of heart disease. They help decrease inflammation and buildup of plaque in arteries, which can lead to an increased risk of heart attack and stroke.
A low-carb diet has been known to lower triglyceride levels as your body uses fat for energy, since your glucose and glycogen levels are decreased due to the diet.
Both low-carb and low-fat diets can help to improve your metabolic syndrome, but a low-carb diet has a more significant effect in reducing the prevalence of metabolic syndrome.
With each gram of fat containing 9 calories (compared to just 4 calories for carbs), many speculate that a low-fat diet will result in a bigger weight loss. While this is sometimes the case, studies have also shown successful results following a low-carb diet, including a higher fat loss while following that diet.
Whether you choose to follow a low-carb or low-fat diet, they are both beneficial in various ways to the body. However, it’s important to remember that while restricting, you should not overdo it. Your body still needs fuel to function properly, and you will need to make up some of the nutrients you’re losing with other foods. Nevertheless, both diets are great strategies for weight loss, and it’s best to stick to them to see your most successful results.
- StatPearls. Low Carbohydrate Diet.
- StatPearls. Low Fat Diet.
- European Journal of Clinical Nutrition. Beyond Weight Loss: A Review of the Therapeutic Uses of Very-Low-Carbohydrate (Ketogenic) Diets.
- Duke Health. Low-Fat Diet Alone Reversed Type 2 Diabetes in Mice.
- PLoS One. Low-Carbohydrate Diets and All-Cause Mortality: A Systematic Review and Meta-Analysis of Observational Studies.
- BioMed Central. Effects of Low Carbohydrate Diet Compared to Low Fat Diet on Reversing the Metabolic Syndrome, Using Ncep Atp Iii Criteria: A Randomized Clinical Trial.