Diet Plus Exercise Equals Diet

The common mantra is “get more exercise”. My question is whether or not exercise helps in weight loss and if so, how much?

Turns out exercise doesn’t help all that much in weight loss.  This study looked at just how much exercise helped in weight loss (Christiansen T1, Paulsen SK, Bruun JM, Pedersen SB, Richelsen B. Exercise training versus diet-induced weight-loss on metabolic risk factors and inflammatory markers in obese subjects: a 12-week randomized intervention study. Am J Physiol Endocrinol Metab. 2010 Apr;298(4).)

The study was 12 weeks long and looked at the effects of diet alone, exercise and diet, and exercise alone. Seventy-nine obese subjects were recruited for the study. They were fed a very low calorie diet and the exercise cohorts were given aerobic exercise three times a week for 60-90 minutes.

Weight loss was virtually identical in the diet only and the diet plus exercise groups. The exercise only group lost significantly less weight.

The key item to note is that both diet and exercise and diet alone both reduced the metabolic syndrome (Insulin Resistance) significantly.

After the intervention, a significant decrease in the number of subjects with the metabolic syndrome was observed in both the DIO group and the DEX group (both P < 0.05; Table 2).

In fact, the Glucose level and Insulin Resistance was more improved in the diet only (DIO) group than in the diet plus exercise (DEX) group.

So you might want to consider the advantages of Diet Only although it looks as if Diet plus Exercise won’t hurt your numbers too badly.

To be fair the exercise groups did have a positive benefit to their health:

Subjects in the EXO and DEX groups increased their VO2max
with 18 and 14%.

A good article (Julia Belluz and Javier Zarracina. Why you shouldn’t exercise to lose weight, explained with 60+ studies. Vox, Updated Oct 31, 2017.).

 

Does Exercise Increase Energy Expenditure While Dieting?

Here is a study that looked at resting energy expenditure (REE) under a calorie restricted diet (L C Henson D C Poole C P Donahoe D Heber. Effects of exercise training on resting energy expenditure during caloric restriction. The American Journal of Clinical Nutrition, Volume 46, Issue 6, 1 December 1987, Pages 893–899).

The seven subjects were moderately obese women put on a calorie restricted diet. The test was lasted nine weeks. They were exercised for three weeks at the end of their diet at 70% of their VO2max.

Resting energy expenditure (REE), maximum oxygen uptake (VO2max), and body composition were measured in seven moderately obese women during 9 wk of dietary restriction (800 kcal/d). During weeks 4-6, subjects underwent exercise training (30 min cycling/d, 5 d/wk, at 70% VO2max).

The conclusions were:

The first 3 wk of caloric restriction decreased REE by 13% (from 1437 +/- 76 to 1254 +/- 66 kcal/24 h, means +/- SEM, p less than 0.05).

That shouldn’t be a surprise since weight loss results in a reduction of Energy Expenditure.  The numbers need to be compared closely to the actual weight loss to see how much of the reduction in TDEE was from the weight difference and how much was from metabolic adaptation.

How was their performance affected?

Exercise training increased VO2max (from 1717 +/- 108 to 1960 +/- 120 mL/min, means +/- SEM, p less than 0.05)

Their VO2max showed a substantial improvement for only three weeks of training. It would have been interesting to have a control group which was not put on the exercise program to tease out whether some of this was due to weight reduction or it was due to the exercise.

but did not elevate the dietary-depressed REE (from 1254 +/- 66 to 1262 +/- 62 kcal/24 h).

It looks like the REE did show an increase but it was not statistically significant.

The greatest decrease in body fat (3.7 +/- 0.4 kg) occurred during exercise training, resulting in a small apparent increase in REE when expressed per kilogram total body weight. However, expressed per unit lean body mass, REE remained suppressed throughout the period of caloric restriction.

At 70% of VO2max they were at a good rate for loss of both carbohydrates and fat stores. It would be interesting to see their actual rates of substrate metabolism.

Their conclusions?

We conclude that exercise training of sufficient intensity to substantially increase VO2max does not reverse the dietary-induced depression of REE.

This is interesting since there’s a common assumption that exercising will cause people to burn more calories at rest but that wasn’t the case in this particular situation.

However, the increase in VO2max itself was worthwhile as it indicates a gain in fitness.

 

Exercise Studies

This will be an accumulated list of exercise related studies.

Athletic performance on Low Carb

Exercise and Diabetes

Exercise Physiology (Mechanisms)

Exercise Supplementation

 

Splitting Low Carb Studies BLOG into Two Sites

The Low Carb Studies BLOG is being split into two sites. The original Low Carb Studies BLOG will concentrate on the Low Carb/Ketogenic diet. This site will focus on Athletics on the Ketogenic Diet.

It will take a while to move the content over but allow more focus on each subject individually.