Low-Carb vs. Low-Fat: Science Reveals Which Diet Is Better for Weight Loss and Diabetes Control

Obesity Weight Loss Concept

Low-carb diet may help patients with diabetes achieve better weight loss and glucose control compared to a low-fat diet.

Patients achieved better weight loss and glucose control over a 6-month intervention with a low-carbohydrate, high-fat, calorie unrestricted diet compared to a high-carb, low-fat diet. This is according to a randomized controlled trial of more than 100 people with type 2 diabetes. The changes were not sustained 3 months after the intervention, suggesting a need for long-term dietary changes to maintain meaningful health benefits. The findings were published in the Annals of Internal Medicine on December 13.

More than 480 million people worldwide are affected by type 2 diabetes. Just in the United States, more than 37 million people have diabetes, according to the American Diabetes Association. More than half of persons with diabetes also have nonalcoholic fatty liver disease (NAFLD), which can progress to cirrhosis and impair liver function. Prior studies suggest that weight loss improves both diabetes control and NAFLD and restriction of carbohydrate intake improves the control of blood sugar levels.

Scientists from the University of Southern Denmark in Odense, Denmark, randomly assigned 165 people with type 2 diabetes to either a low carb high fat (LCHF) diet or a high carb low fat (HCLF) diet for 6 months. Participants in both groups were asked to eat the same number of calories equal to their energy expenditure. Patients on the low-carb diet were instructed to consume no more than 20% of their calories from carbohydrates but they could have 50-60% of their calories from fat and 20-30% from protein. Participants on the low-fat diet were asked to eat about half of their calories in carbohydrates and the rest evenly split between fats and proteins.

The authors found that people on the low-carb diet reduced hemoglobin A1c by 0.59 percent more than the low-fat diet, and also lost 3.8 kg (8.4 pounds) more weight compared to those in the low-fat group. The low-carb dieters also lost more body fat and reduced their waist circumference. Both groups had higher high-density lipoprotein cholesterol and lower triglycerides at 6 months.

However, changes were not sustained 3 months after the intervention, suggesting that dietary changes need to be sustained over the long term to maintain effects. The liver was not affected by the high fat intake in the low-carb group: The researchers found no difference in the amount of liver fat or inflammation between the two groups.

Reference: “Effect of Calorie-Unrestricted Low-Carbohydrate, High-Fat Diet Versus High-Carbohydrate, Low-Fat Diet on Type 2 Diabetes and Nonalcoholic Fatty Liver Disease: A Randomized Controlled Trial” by Camilla Dalby Hansen, MD, Eva-Marie Gram-Kampmann, MD, Johanne Kragh Hansen, MD, Mie Balle Hugger, MD, Bjørn Stæhr Madsen, MD, PhD, Jane Møller Jensen, RD, Sara Olesen, MD, Nikolaj Torp, MD, Ditlev Nytoft Rasmussen, MD, PhD, Maria Kjærgaard, MD, Stine Johansen, MBBS, Katrine Prier Lindvig, MD, Peter Andersen, MSc, Katrine Holtz Thorhauge, MD, Jan Christian Brønd, cand.scient, PhD, Pernille Hermann, MD, PhD, Henning Beck-Nielsen, MD, DMSc, Sönke Detlefsen, MD, PhD, Torben Hansen, MD, PhD, Kurt Højlund, MD, DMSc, Maja Sofie Thiele, MD, PhD, Mads Israelsen, MD, PhD and Aleksander Krag, MD, PhD, 13 December 2022, Annals of Internal Medicine.
DOI: 10.7326/M22-1787

39 Comments on "Low-Carb vs. Low-Fat: Science Reveals Which Diet Is Better for Weight Loss and Diabetes Control"

  1. Marilyn Morcilio | December 16, 2022 at 8:28 am | Reply

    What kind of food that I can eat that is not carb and low fat please tell me so I know and make it in my house

  2. Photoshopping photos for weight loss articles is highly unethical.

  3. Keto IS the way to go. At age 64, I easily dropped 57 pounds in 5months and have kept it off for over a year now. No hunger at all between meals.

  4. As a trainer & weight loss specialist this is old news & has been known for a long time. Ho hum. For those who think keto is the way to go know this: yes, keto can help you lose weight because it basically removes most sugars that cause metabolic slowdown, but as a sustainable lifestyle it’s a no. Why?it lacks some vitamins, minerals, and phytochemicals that are important for long term health; having said that, there are some who can sustain a keto diet and do fine, but doubtful they will live longer than those on a “blue zone” diet, mostly plant based & considerably higher in carbs. Research is actually very limited in keto (i.e., 20 years+), but until there’s more data I’ll stick with the Mediterranean style diet which statically is the current champion of lifestyle nutrition

  5. Tapio Angervuori | December 17, 2022 at 7:07 am | Reply

    Eat accordingly to the food pyramid less than you consume. This way you will certanly loose weigth insted of water. Allso Your glucose levels will sink. Eat a starch rich meal and consume water insted of alcoholic beverages in the evening. You will sleep well during the night.

  6. @R.A Freedman Keto is completely sustainable. It’s very easy : just eat meat and low carb vegetables. Simple and delicious.
    The only problem is eating out and cultural norms about festive foods.

  7. Josef Renaude, MD PhD | December 17, 2022 at 11:12 am | Reply

    I will eat what homosapiens have eaten for 2 million years, since they departed lineage with chimps. Just because our collective intelligence lead us to start eating plants, our physical bodies are totally uneqipped to handle the breakdown of plants, the andorbtion of plant nutrients, nor the high toxins found in plants. Fatty meat and zero sugars wins the contest every time. Embrace your humanity- eat meat.

  8. High protein and weight training is the way to go 😄

  9. A high fat all meat carnivore diet is the only way to go if you want to fix your diabetes, ADHD in children and adults, depression, any autoimmune disease, and many other health issues can be fixed by this diet and lose weight and be healthy. This has been a known fact for thousands of years meet and eggs and a little dairy. good luck

  10. I’m surprised someone actually did this study. I’m not a nutritionist, but this has been obvious for decades! The so called “low fat” diet is a long scam pushed onto Americans by one noisy doctor from the 1960s. And even though his observational study has been debunked many times, this fallacy is still pushed onto people.

  11. Define Carb. Simple or complex?

  12. I think it is a little of everything does you no harm. We all need the nutrients found in meat, dairy and plants. So a balanced diet, cut out over indulgence in sweets, chocolates etc keep them as occasional treats. Same with alcohol, all things in moderation. Following a mainly Mediterranean diet, and eating more fish that red meat is the way foreword and do some exercise too, but again don’t overdo that .. you don’t need to be training for the Olympics!

  13. Science says? You mean the same science that told us to eat omega 6 fats instead of animal fats and is responsible for untold deaths and injury to millions as a result?
    That science? I’ll think for myself.

  14. So refreshing to see people talk about the virtues of fat, meat and vegetables for carbs, or at least reducing simple carbs. Blows my mind that society still pushes low fat crap. Here’s another thing… real ingredients, i.e., if you feel like a cup cake occasionally then eat a damn cupcake, just make sure it’s made with real, wholesome, non-processed ingredients. It’ll even get rid of your inflammation, which may be impacting sleep quality (snoring and apnea). I’m 57 and have the strong body, endurance and spirit of a fit 30 year old. It works, stop falling prey to the CPG and pharma marketing machines people.

  15. Charles Morrison | December 18, 2022 at 9:02 am | Reply

    This article is not factual at all. A high fat low carb diet promotes insulin resistance asany studies that I have read has shown. I myself dropped 120 pounds 10 years ago and cured my diabetes.I did it with a diet of 75 to 95 percent carbohydrates from whole plant food. It is intermyocellular lipids that causes diabetes. That is excess fat in the cells which prohibits the insulin from bringing glucose into the cells as they are intended to do. I am so tired of this misinformation like what is found in this article

  16. I amazed at all the misinformation shared in this thread by “experts”. Do your own research and consult with an RD within your healthcare system. They’ll have a better idea of your incidentals, history and goals. And create a custom plan for you.

  17. Maybe they would have had better results in the liver if they actually gone low carb. 😂 Like cmon: 20% carb is still high in carbohydrates compared to those that are actually on low carb diets in real life. For example, the ketogenic diet is only 5% carbs maximum: usually 30g total carbs and 15 net carbs. Those who knows what’s up try to keep it as close to zero grams as much as possible.

    I read this briefly, but I don’t think I saw the studies differentiating the types of carbs even as well: like total carbs and net carbs. Sugar is like the most legal drug ever, so of course it’s not sustainable if you give them a 5-20% addictive substance. The liver has to clear those first before even starting to clear its own fat. Hence, this study is definitely lacking and missed out on a great opportunity to further advance science.

    There was another, longer study that saw a reverse in diabetes or lower medication needed after 8 months of a real low carbs diet of 80% of its participants. And guess what? They only advised the participants. 👏 Didn’t 👏even 👏have 👏to 👏spoon👏 feed👏 them 👏this 👏preposterous 👏 20%👏 carbs👏 diet.

  18. I’m 73 years old was a type 2 diabetic for twenty years, I have now reversed my diabetes and have stopped all diabetic medication. I am low carb, high fat, carnivore. I will embrace this lifestyle change until my last breath. It is time for the medical community to become more involved with proper nutrition care for all patients and get to root of the rather than handing out a pill. People need to rely on themselves and stop looking for quick fixes.

  19. Low fat can kiss my ace. I’ve been living a low-carb lifestyle for 7.5 years now and will never go back.

  20. @Tapio Angervuori
    Seems like you may not have read the article.
    You say to follow the food pyramid and “lose weight not water”…. In the article, they flat out state that measurements were taken. The low carb group lost more body fat and had a greater reduction is waist circumference than the low fat group.

    And the people claiming that high fat diets cause diabetes are referring to misinterpreted science. The only time a high fat diet will cause diabetes, is if you have too many carbs with your fats, or if you are eating unhealthy fats (seed oils and processed trans fats)

  21. This or keto is a great start to lose weight but notice it doesn’t help with non alcoholic fatty liver disease. Look into fasting mimicking diet. 3 rounds 1 times a month 5 days at a time can reverse diabetes and fatty liver. It also lowers inflammation so if you have an auto immune disease then you’ll likely see improvement. It also helps lengthen telemers. It was created by a longevity doctor. I’d recommend FMD then the Mediterranean diet lifestyle.

  22. It not as simple as low carb. Health and weight loss is all about keeping insulin level low for many contiguous hours at a time. Carbo fasting restricts carb intake to one or two meals a day. Enjoy your carbs, just don’t eat them all day long.

  23. This is very ild news in the U.S.! Carbs add sugar to the blood sooner and they burn faster than proteins and fat;that’s been known for decades. Denmark is way behind, I guess. It goes, Fastest: sugar, ordinary sugar (cane) then fruit & milk sugars; Fast: ‘plain carbs’ like white bread, then more complex carbs like whole wheat; Slower: proteins; Slowest; Fats.

  24. No, do not follow the food pyramid. That was skewed a long time ago. The food industry paid a lot of money in order to make money off of us not knowing any better. The one thing you need to know about a low fat diet is that the brain has to have fat to function. Maybe the reason for the increase Alzheimer’s and Dementia

  25. The real secret is eat whole foods, nothing processed. Eat until your full and you won’t snack in between meals.

  26. I guess these authors don’t care about the research that has concluded that all forms of dieting lead to poor long term physical health outcomes, disordered eating, eating disorders, and mental health issues. As long as you lose weight (temporarily), everything is sunshine and roses.

  27. Sheldon Boucher | December 20, 2022 at 8:58 am | Reply

    Keto diet is NOT sustainable. There is no long term data relating to safety of this diet, and there is a plethora of side effects. It is the Atkins diet repackaged and repurposed to seem legitimate, but it is not. Cutting out an entire macronutrient is not a sustainable diet. Cut out fruit? Sorry, but good luck making the argument that fruit are in any way bad for you. By cutting out carbs as entire group, you are missing out on a sh*tload of important nutrients, vitamins and antioxidants, stressing out your kidneys and arteries in the process. Yes, you will lose weight, but when the fu** did weight loss become the key metric of longevity? It’s a simplistic diet for a simplistic way of looking at human health and it’s sad people actually believe it’s at all sustainable or healthy based on current data.

    Say NO to Keto. Do the research and try and find one study of long term effectiveness and safety.

  28. It’s not about cutting carbs or fat. It’s about the order you eat. Eating carbs with fat will always store fat since your using the carbs as energy. But if you eat fat alone it will be used immediately and vice versa with carbs. So don’t eat those two together and you’ll notice a difference

  29. What if you want to eat a low carb diet but often become hypoglycemic?

  30. Low carb dieting totally changed my eating habits. Being on the diet for a year, I lost 60 pounds. I started to enjoy eating all foods because my taste was more sensitive to the natural carbs in food especially vegetables and I was never hungry because I ate when I wanted to eat. Admittedly once you start a low carb diet, you can never fully go off. It’s like the chip you can’t eat just one. High carb foods can quickly reverse your gains, they are like a drug. I am always selective when choosing what to eat but will splurge at times as an award. I have my ups and downs the past 20 years and I’m still 45 pounds down from where I started.

  31. Since I don’t have a gallbladder,the higher fat in Keto did not always agree with my stomach. I metabolic doctor said it puts the body into a burn cycle to eat three or four small meals a day that are balanced. A diet that is low fat, medium/low in carbs, and med/low in calories depending on the BMI. The diet consist of about 1/3 carbs, 1/3 lean proteins, and 1/3 of everything else like green, or non starchy vegetables and low fat milk products for breakfast with fruit low or no sugar. My mother is a hypoglycemic and when she tried the Keto her blood sugar levels dropped so low that it caused her to start to have neuropathy pains for the first time. This burn cycle diet helped her too. It was made for people that eat too much fat or too much sugar or no vegetables. Or, not enough and starve themselves

  32. I have tried Evey thing even tablets, and nothing. I don’t want to give up, but l am lost now.

  33. I know a few women on Keto who eat lots of meat, bacon, etc yes they have lost lots of weight but my conces the dirty meat. I’ve read articles about the meat we eat came from animal’s who were injected with toxic chemicals to make them bigger than they normally would be.

  34. I need help! There’s so much information out here and I’m not sure what to follow for weight loss. I need to lose at least 50 lbs. I’m fighting for my life.

  35. Why the big focus on it was not sustained. Duh. If you do eating that way and go back to eating unhealthily then you will go back to your old problems. Why would they keep saying that. If course it has to be a life long change. Is that supposed to be a flaw?

  36. Do what works for your body

  37. Well I was 298 before the great covid and I’m tyep 2 diabetes and KETO saved my life A1C was 9.5 I’m down to 214Lbs and all these years Dr’s have been lying to you and me every body is a different world.Meat chess eggs some vegetables milk. Carbs are not good for my body.

  38. This article doesn’t specify if the high carb diet is plant based or meat eating. I’d love for plant based to have been covered in the high carb group. I have lost weight on a low fat diet (with low impact exercise) in my late 20s so I can’t rule that out

  39. Just read The China Study. I can’t imagine trusting a study that is short term and only used 100 people, most likely from the same geographic location. In the China study it was done over 40 years in study length, with thousands of people WORLDWIDE. Wake up people. These industry funded studies shoving fat down our throats is WHY HEART DISEASE IS SKYROCKETING AND WHY OUR KIDS ARE OBESE AND WHY WE ARE SICKER THAN EVER. Don’t be nutrionaly ignorant.

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