Skip To Main Content

COVID-19 Updates and Resources. Learn More

Pilot 12-Week Weight-Loss Comparison: Low-Fat versus Low-Carbohydrate (Ketogenic) Diets

The following summarizes information presented at multiple conferences on a pilot study conducted by Greene et al. This information was written by Atkins professionals.

Obesity Research

Greene, P., Willett, W., Devecis, J., et al., "Pilot 12-Week Feeding Weight-Loss Comparison: Low-Fat vs Low-Carbohydrate (Ketogenic) Diets," Abstract Presented at The North American Association for the Study of Obesity Annual Meeting 2003, Obesity Research, 11S, 2003, page 95OR.

Greene, P.J., Devecis, J., Willett, W.C., "Effects of Low-Fat Vs Ultra-Low-Carbohydrate Weight-Loss Diets: A 12-Week Pilot Feeding Study," abstract presented at Nutrition Week 2004, February 9-12, 2004, in Las Vegas, Nevada.

Summary:

BACKGROUND:

Some researchers claim that people only lose weight on very low carb diets due to a reduction in calorie intake. Others have argued that very low carb diets offer a “metabolic advantage” allowing people to lose weight without restricting calories. The objective of this study was to evaluate if people who follow very low carb diets lose weight only due to restricting calories.

METHOD:

Twenty-one participants were recruited and were randomly assigned to three separate diets for 12 weeks: a low fat diet (55% carb, 15% protein, and 30% fat) and two different very low carb diets (both had 5% carb, 30% protein, and 65% fat). The low fat (LF) diet and one of the very low carb (LC1) diets provided a total of 1500 calories a day for women and 1800 calories a day for men. The second very low carb diet group was allowed 300 additional calories a day (1800 calories for women and 2100 calories for men). Meals were provided during the study.

RESULTS:

After 12 weeks, all participants lost weight. Both the very low carb groups lost more weight than the low fat group (LC1: -23 lbs, LC2: -20 lbs, and LF: -17 lbs). The difference between the diets was not statistically significant. More body fat was lost than lean body mass (such as muscle) or water on all the diets. All participants lost inches from their waist and hips.

CONCLUSION:

All three diets were effective in reducing weight in adults and the weight lost was primarily body fat. Even participants consuming higher calories on the very low carb diet were able to lose more weight compared to the lower calorie, low fat diet. Several risk factors for heart disease improved on all diets. The authors concluded that very low carb diets do not reduce weight only by restricting calories.

Commentary:

The following information was written by Atkins professionals.

Individuals followed one of three diets: a low fat, calorie controlled diet (1500 calories women/1800 men), a low carb, calorie controlled diet (1500 calories women/1800 men), or a low carb diet containing 300 additional calories a day (1800 women/2100 men). Individuals following a low carb diet (5% carbohydrate, 30% protein, 65% fat) lost weight regardless of whether calories were restricted. Weight loss in both low carb groups was greater than for those following a low fat diet (55% carbohydrate, 15% protein, 30% fat). These results suggest that a low carb diet, with or without caloric restriction, produces greater weight loss than a low fat diet.

Try a More Flexible Keto

Atkins keto plans are more flexible and more personalized to provide a long-term plan for reaching your goals. Our free tools can help you even further.

Get Started

Learn More About Low Carb Articles & Research

Low Carb and Keto Alcohol Drinks - What to Order

Whether you’re out at a bar or fixing yourself a drink at home, there are plenty of options to stay true to your low carb or keto lifestyle—especially if you have the added versatility of a flexible ketogenic diet like Atkins20 ® or Atkins40 ® *.

Read More »

Low Carb and Keto Fast Food Options

Following a low carb lifestyle doesn’t mean you have to sacrifice the on-the-go convenience of fast food.

Read More »

Stay at Home, Stay on Track: How to Eat Healthy at Home While You're Social Distancing

Practicing social distancing to limit the spread of COVID-19 has left many of us staring at our pantries, wondering what to make—especially if you, like many Americans, rely on take-out or delivery for most of your meals.

Read More »

What Breaks an Intermittent Fast?

If you're new to intermittent fasting , you may have a lot of questions about what to do while fasting 1 .

Read More »