Diet vs. Exercise In The Game Of Fatloss

The popular debate that surfaced this past year was between the role of exercise in fat loss. It basically started with Time Magazine running an article titled Why Exercise Wont Make You Thin. Right when the article came out, it began an internet firestorm from health professionals blogging about how horrible Time Magazine was for publishing this article – talk about going viral!I read the article a few days after it came out and to tell you the truth, it wasn’t that bad! In reality, all it was saying was what we basically already know, “you can’t out work a poor diet.”

I am not going to dispute that diet is an important component to losing fat. In fact, it is the most important component as far as I am concerned. We have all seen those people in the gym who kill themselves 2 hours a day/7 days a week, yet see minimal to no results because they are constantly over-eating.

While diet is important for losing fat, exercise is essential for achieving higher levels of health. Together, an appropriate calorie-restricted diet and a sound exercise program are essential not only for improving body composition, but also improving the overall function of the body’s systems.

Researchers at the Pennigton Biomedical Research Center at Louisiana State University recently evaluated the results of caloric restriction with or without exercise.

Thirty-six overweight participants (16 males/20 females) were randomly assigned to one of three groups for the 6-month study:

1. A control group who ate a weight-maintenance healthy diet
2. A caloric restriction group who restricted energy intake by eating at a daily caloric deficit of 25%
3. A caloric restriction plus exercise group who created a daily caloric deficit of 25% by reducing energy intake by 12.5% and increasing energy expenditure by 12.5%

The researchers posed the following question:

“Does caloric restriction with or without exercise result in different improvements in cardiometabolic risk factors which could ultimately improve longevity? The purpose of this analysis was to determine whether a deficit by energy restriction or energy restriction plus aerobic exercise that produces equal change in fatness leads to greater cardiometabolic benefits when exercise is included.”

The Diet

The diets used in the study where based on the America Heart Association’s Step 1 recommendations.

During the first 12 weeks of the study food was provided for all groups based on their dietary needs. In weeks 13-22 the subjects self-selected their own diet based on their individual caloric target, and in weeks 22-24 (the final two weeks of the study) the subjects returned to the in-feeding protocol, which they used in the fist 12 weeks.

The Exercise

Both the control group and the caloric restriction only group where not allowed to alter their current level of physical activity for the 6-month study.

The caloric restriction plus exercise group was required to increase their energy expenditure by 12.5% above their baseline requirements. They did so by partaking in a structured aerobic exercise program (IE, walking, running or stationary cycling) for 5 days a week.


Adherence is a common problem in studies like this, and subjects are notorious for under-reporting their caloric intake and over-reporting their caloric-expenditure.

The subjects in this study attended weekly group meetings and were contacted once per week via telephone to ensure there were no adherence problems to the program.


The subjects were tested for changes in fat mass, visceral fat, Vo2 peak (using a graded treadmill test), muscular strength (isokinetic knee extension/flexion), blood lipids, blood pressure, and insulin sensitivity/secretion.

Aerobic Fitness and Muscle Strength Results

The exercise group was the only group that saw improvements in Vo2 peak, which is to be expected since they were the only group stressing their aerobic fitness.

There were no changes in muscle strength between the groups. This would be expected considering this study did not have a resistance training component to it.

Body Composition Results

Body fat was significantly reduced in both the caloric restriction and caloric restriction plus exercise groups, as were total body fat mass and visceral abdominal fat.

People may look at those results and think that those results aren’t very promising for the exercise group; however, I look at those results and see what I would expect to see given that both groups had created an equal caloric deficit (25%).

Cardiometabolic Risk Factors

This is where, in my opinion, things get important.

HDL (the “good” cholesterol) was significantly increased in all treatment groups, including the control group. This is possibly because their diet was set up for them based on the American Heart Association guidelines. And even though they were not eating in a caloric deficit – rather eating at a weight-maintenance level – the diet was probably healthier than the normal junk they would eat on a daily basis.

Fasting serum triglyceride concentration increased significantly in the control group, but decreased significantly in both the caloric restriction and the caloric restriction plus exercise groups.

While systolic blood pressure was not changed in any of the groups, diastolic blood pressure, total cholesterol, LDL (the “bad” cholesterol), and insulin sensitivity were significantly improved ONLY in the caloric restriction plus exercise group!


– Adding exercise to your calorie-restricted fat-loss diet has greater improvements on cardiometabolic health, which are greater than caloric restriction alone.

– The addition of aerobic exercise to a calorie-restricted diet enhances overall aerobic fitness which is helpful for improving health and wellness.

– Calorie restriction is essential for fat loss and body composition changes; however, when combined with exercise, the amount of caloric restriction needed to illicit the same results in body composition is decreased (12.5% caloric restriction with exercise intervention vs. 25% caloric restriction with no exercise).

– Aerobic exercise has been shown to improve insulin sensitivity, which is important in the health of overweight/obese individuals who may be at greater risk for diabetes and/or other metabolic disorders.


Calorie restriction is king when it comes to fat loss. A proper diet will help you achieve this goal, but exercise can be effective in not only helping you reach this goal (without having to rely as heavily on reducing calories, which typically leads to a miserable experience and lack of adherence) but also, in helping improve your overall cardiovascular and metabolic health.

About the Author:
Patrick Ward holds a Masters Degree in Exercise Science. He is a Certified Strength and Conditioning Specialist (CSCS) through the National Strength and Conditioning Association (NSCA) and a USA Weightlifting-Certified Club Coach. In addition, Patrick is a licensed massage therapist focusing on Neuromuscular therapy and Active Release Techniques (ART). He lives in Chandler, Arizona and is the owner of Optimum Sports Performance and the Co-founder of Reality Based Fitness. He can be reached at Visit website:


Larson-Meyer DE, Redman L, Heilbronn LK, Martin CK, Ravussin E. Caloric restriction with or without exercise: The fitness versus fatness debate. Med Sci Sports Exerc 2010;42(1):152-159.