Recent Study Shows Low Carb Diets More Effective Than Low Fat Diets Long Term

Monday, July 28th, 2008 | Fat Loss, Nutrition

A recent study in the New England Journal of Medicine showed better fat loss over the long run with low-carb and “Mediterranean” diets than a low-fat diet (Shai I, Schwarzfuchs D, Henkin Y, Shahar DR, Witkow S, Greenberg I, Golan R, Fraser D, Bolotin A, Vardi H, Tangi-Rozental O, Zuk-Ramot R, Sarusi B, Brickner D, Schwartz Z, Sheiner E, Marko R, Katorza E, Thiery J, Fiedler GM, Blüher M, Stumvoll M, Stampfer MJ. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med. 2008 Jul 17;359(3):229-41.)

ABSTRACT

Background Trials comparing the effectiveness and safety of weight-loss diets are frequently limited by short follow-up times and high dropout rates.

Methods In this 2-year trial, we randomly assigned 322 moderately obese subjects (mean age, 52 years; mean body-mass index [the weight in kilograms divided by the square of the height in meters],31; male sex, 86%) to one of three diets: low-fat, restricted-calorie; Mediterranean, restricted-calorie; or low-carbohydrate, non–restricted-calorie.

Results The rate of adherence to a study diet was 95.4% at 1 year and 84.6% at 2 years. The Mediterranean-diet group consumed the largest amounts of dietary fiber and had the highest ratio of monounsaturated to saturated fat (P<0.05 for all comparisons among treatment groups). The low-carbohydrate group consumed the smallest amount of carbohydrates and the largest amounts of fat, protein, and cholesterol and had the highest percentage of participants with detectable urinary ketones (P<0.05 for all comparisons among treatment groups). The mean weight loss was 2.9 kg for the low-fat group, 4.4 kg for the Mediterranean-diet group, and 4.7 kg for the low-carbohydrate group (P<0.001 for the interaction between diet group and time); among the 272 participants who completed the intervention, the mean weight losses were 3.3 kg, 4.6 kg, and 5.5 kg, respectively. The relative reduction in the ratio of total cholesterol to high-density lipoprotein cholesterol was 20% in the low-carbohydrate group and 12% in the low-fat group (P=0.01). Among the 36 subjects with diabetes, changes in fasting plasma glucose and insulin levels were more favorable among those assigned to the Mediterranean diet than among those assigned to the low-fat diet (P<0.001 for the interaction among diabetes and Mediterranean diet and time with respect to fasting glucose levels).

Conclusions Mediterranean and low-carbohydrate diets may be effective alternatives to low-fat diets. The more favorable effects on lipids (with the low-carbohydrate diet) and on glycemic control (with the Mediterranean diet) suggest that personal preferences and metabolic considerations might inform individualized tailoring of dietary interventions.

What’s most interesting about this is, despite the low-carb group not being restricted to a specific daily calorie intake like the Mediterranean and low-fat groups (1,800 calories per day for men, 1,500 for women), but rather limiting carbohydrates to 20 grams per day for the first two months followed by 120 grams per day, and despite being advised to choose vegetarian sources of protein, which are generally lower quality than animal sources, they had the greatest weight loss. Additionally, the low-carb group had the greatest increases in HDL and greatest decreases in triglyceride levels. The low-carb group also had the greatest decrease in the ratio of total cholesterol to HDL, nearly twice that of the low-fat group (20% versus 12%).

I am surprised the weight loss for each of the groups was so low based on the calorie and carbohydrate intake guidelines, and strongly suspect poor compliance, very sedentary subjects, or both. If the subjects were actually following the guidelines I expect the weight loss would have been far greater for all groups.

I am also disappointed the dietitians advised the low-carb group to choose vegetarian sources of protein, as I suspect better weight loss and at least equal improvements in lipid profiles had animal sources been chosen.

In any case, it is further proof of the benefits of a higher-protein, lower-carbohydrate diet and it’s viability as an alternative to high-carb, low-fat diets. I have consistently seen better results in my own training and with my personal training clients with higher-protein and lower-carbohydrate intakes.

Tags: , , , , , , , , , , , , , , ,

7 Comments to Recent Study Shows Low Carb Diets More Effective Than Low Fat Diets Long Term

Danny
July 28, 2008

Low carb eating has one primary factor that might contribute to it’s success:

The body must consume external sources of protein -the 8 necessary amino acids. It can manufacture other amino acids from that.

It can manufacture lipids and other fatty acids from proteins. While other sources of lipids are desirable, they’re not necessary…sorta.

The body can manufacture carbohydrates from protein and fat.

The body NEEDS protein consumption. It does not NEED carbs or fat. It does better with balance (unless you’re Nordic, Siberian, or Inuit).

The HIT crowd, and other dietary conservatives maintain that a calorie is a calorie. In terms how how much energy it takes to heat water, this would be true. But, when you apply a simple calculation to an incredibly complex biological environment, you’ll encounter more variables than your great-great-great grandchildren will be able to deal with.

That said, I’m not maintaining that low carb eating is a better choice for fat loss. It might be for some, might not for others.

In my experience, the single best tool/method for fat loss is to plan your daily eating at least one day ahead of time.

If the participants followed even a simple meal plan, THAT was the contribution to their success. The same with any diet plan.

Ryan Del Curto
July 28, 2008

Greetings Mr. Baye, I’ve read your other articles and I was hoping you’d post something on the high/low carb debate. I’ve read some of the study in your article (haven’t had time to read it all) and I was wondering about your interpretation of the following:
The low fat group had 30% of its calories from fat, higher than most low fat diets, do you think that played a factor in its poor performance? Personally, I still think energy balance is king in terms of weight loss, so I don’t know if this mattered much.

I’ve read that protein has a higher ‘thermic effect’ than either fats or carbohydrates, so you effectively net fewer calories in terms of energy for fat storage or use than an equivalent amount of fat or carbs, do you think this is why high protein/low carb diets outperform other diets?

One final question, are you aware of any studies examining the effects of low carb/ high protein diets on blood chemistry (triglycerides, cholesteral etc)in healthy subjects not trying to lose weight? I ask because I think weight loss is a significant factor in these measurements so to speculate if low carb/high protein diets are healthy long term, I would think weight loss would need to be eliminated or controlled so as not to confound the results.

Drew Baye
July 28, 2008

Ryan,

I think the poor results were due to non-compliance in all groups. If the subjects in the Mediterranean and low-fat groups consistently consumed the amount of calories they were supposed to the weight loss should have been much greater.

Higher protein intakes provide several benefits. The greater thermic effect may make a difference over longer time periods. The increased satiety with higher protein intakes helps to reduce total calorie intake. Higher protein intake should help offset the increased rate of protein breakdown resulting from the reduced calorie intake, helping to maintain lean body mass.

Often, when people diet, they make the mistake of reducing intake of all macronutrients proportionally. A better approach would be to maintain or even increase protein intake while calories are reduced. Lyle McDonald talks a bit about this in his Protein Book, which I highly recommend. I will be posting an interview with Lyle on this and a few other subjects within the next few weeks.

Ed Jones
August 4, 2008

The body NEEDS protein consumption. It does not NEED carbs or fat. It does better with balance (unless you’re Nordic, Siberian, or Inuit).

Danny,
I’m curious about this statement. Could you elorate, as Iam od Swedish extraction I would enjoy learning something about mt possible “different” dietary needs.
Thanks.
I do appreciaate it.

Joe
August 7, 2008

Bodies need protein, fat, and carbohydrates. Without any one of the three you will die. The main advantage I see with a low carb diet is that it forces one to eat well-balanced meals. Very few foods have only protein, but lots of (refined) foods have essentially only carbs. So fewer refined food leads to a diet closer to what our bodies are designed to consume.

The quality of protein from animal versus plant sources is probably not a major issue. Eggs might be the richest source of digestible protein, but legumes are still very rich sources of protein. If you have a well varied diet, your body will make everything work.

Drew Baye
August 7, 2008

The body does need carbohydrates, but it can make these out of protein (gluconeogenesis) so they do not have to be consumed in the diet. The only things that need to be consumed are protein (essential amino acids), fats (essential fatty acids), water, vitamins and minerals.

Chris Collins
November 17, 2008

Really interesting study. This coincides with information i have read out about the history of research into diet. For example, an interesting but little known fact i know concerns a quote from Hans Krebs (discoverer of the Citric Acid Cycle/ Krebs Cycle) on energy metabolism in the muscles and indeed the body as a whole. He’s quoted in ‘The Diet Delusion’ by Gary Taubes, which by the way is an immense tome on all things nutrition with 60 pages worth of scientific references, i cannot recommend it highly enough.

Quote: ‘Krebs had initiated his his research assuming, as was common at the time, that carbohydrate was ”the main energy source of muscle tissue”. But he came to realize that fat and protein also supply fuel for muscle tissue, and that there was no reason why carbohydrates should be the preferred fuel. ”all three major constituents of food supply carbon atoms…for combustion,” he wrote.’

This contradicts a popular notion amongst nutritionists that you must have 60% of your daily intake from carbohydrates.
The book also contains many examples of research which again demonsrates the apparent effectiveness of restricting carbohydrates, be they simple or complex.

thanks for reading

Chris

Leave a comment