As in the first study, diets were not prescribed individually or controlled for adequately in the data analyses. Therefore, it is difficult to assess the degree of calorie and protein restriction, and the effect these variables may have on the initial reduction in metabolic rate and subsequent maintenance of it.
According to the description of recommended dietary intake during the first phase of the study, protein intakes may have been as low as 0. This level of restriction may partially explain why fat-free mass and resting metabolic rate did not increase in the resistance training group. The researchers of this study have concluded that attenuating the reductions in resting metabolic rate and increasing fat oxidation rates after weight loss are not the mechanisms by which exercise prevents weight recidivism.
However, until dietary factors are controlled for, these types of conclusions are premature. Lastly, a third non-exercise group in the post-diet period would have strengthened the study. It would have been interesting to compare the resting metabolic rates and fat oxidation rates of weight-reduced exercisers versus non-exercisers. Gornall J, Villani, RG. Short-term changes in body composition and metabolism with severe dieting and resistance exercise.
Int J Sport Nutr ; 6: — The authors sought to examine the potential of strength training as a means to prevent the decline in fat-free mass and resting metabolic rate associated with very-low calorie diets. They randomly placed 22 female subjects in one of two groups, a diet-only group and a diet plus strength training group. Subjects were matched on body surface area. In addition, the authors controlled for two other factors: fluctuations in metabolic rate due to hormonal changes and losses in total body water.
Women were tested at approximately the same time of the month in their menstrual cycle. Body composition was analysed using a dual X-ray absorptiometry technique which is sensitive to changes in fat-free mass associated with fluctuations in water, minerals and protein.
The treatment period was 4 weeks long, during which time subjects consumed kilocalories per day. All pre-packaged meals were provided to subjects free of charge. Post-intervention tests were completed while participants were still on the very-low-calorie diet. They met with the research staff two times per week for support and weigh-ins.
Those in the diet-plus-exercise group also participated in supervised strength training activities three times per week. They completed three sets of 10 free weight exercises each training session, and resistance was progressively increased. Post-intervention testing was conducted 2 days after the last exercise session. An analysis of variance with repeated measures revealed a significant time effect, such that those in the diet-only group and the diet plus strength training group experienced a significant decrease in kilograms body mass There were no significant group differences, indicating that strength training did not attenuate the reduction in resting metabolic rate or fat-free mass.
In addition, an analysis of changes in absolute resting metabolic rate, controlling for fat-free mass as a covariate, again reveals a significant decrease in resting metabolic rate with no statistically significant differences between groups. In other words, for both groups there is a significant loss in absolute resting metabolic rates above and beyond what can be explained by loss of fat-free mass.
The authors conclude that resistance training cannot reverse the negative effects of severe energy restriction on resting metabolic rate or fat-free mass. In addition, the authors conclude that the majority of fat-free mass lost could be accounted for by loss of body water.
Since carbohydrate is stored in the muscle with water, the loss in body water is expected due to glycogen depletion associated with the hypocaloric diet. Strength training draws largely on locally stored glycogen for energy substrate, and can therefore further decrease the glycogen and water component of fat-free mass. The authors note that the short-term decrease in resting metabolic rate may be due to a decrease in sympathetic tone associated with a diet-induced decrease in circulating insulin levels.
Dietary factors are addressed in this study in that all meals were provided to patients. Patients were consuming approximately 0. Resting metabolic rate was measured while subjects were on the hypocaloric diets, and therefore is reflective of the stress of dieting itself and not simply of the loss of fat-free mass. The authors calculate that all of the loss in fat-free mass can be attributed to water losses.
However, it should be noted that this is likely to be an oversimplification, and measurement errors are probably masking the loss of actual protein or muscle mass.
Therefore, if water losses are not accounted for, the relationship between fat-free mass and resting metabolic rate may not be accurately and completely described. Effects of diet and diet-plus-exercise programs on resting metabolic rate: a meta-analysis. Int J Sport Nutr ; 6: 41— It is difficult to summarize the results of studies examining the effect of exercise on resting metabolic rate during a hypocaloric dieting period due to the number of variables that are involved type, duration, frequency and intensity of exercise, degree of energy deficit, total daily calorie intake, and distribution of calories among carbohydrates, proteins and fats.
Therefore, Thompson and colleagues suggest caution regarding narrative reviews of this body of literature. Rather, they have conducted a meta-analysis to quantify treatment effectiveness, specifically the effects of diet alone and diet-plus-exercise on resting metabolic rate. The authors searched the literature and found 22 studies between and that documented resting metabolic rate in humans placed in either diet-only groups or diet-plus-exercise groups.
The studies represent data from subjects, 68 males and females, 31—45 years of age. The majority of studies placed subjects on low-fat, high-carbohydrate diets of less than kilocalories per day.
Intervention programmes lasted approximately 10 weeks. Effect sizes for differences in resting metabolic rate before and after diet and before and after diet-plus-exercise were calculated. Positive effect sizes indicate that resting metabolic rate increased due to the intervention, and negative effect sizes indicate that resting metabolic rate decreased as a result of the intervention.
When expressed in absolute terms, there was a significant decrease in resting metabolic rate in diet only However, the drop is classified as small for the dieters who exercised and large for those who just dieted. This difference is also statistically significant. Similarly, when expressed per kilogram of fat-free mass per hour, the drops in resting metabolic rate for the dieters 5. The decrease in the dieters is classified as moderate, while the decrease with dieter— exercisers is considered small.
The difference between groups is not significantly different. The authors were also able to establish that neither diet-related variables number of calories, distribution of calories among macronutrients or duration of diet , exercise-related variables type of exercise, intensity, duration or frequency nor subject-related variables age, gender, body composition correlated significantly with changes in resting metabolic rate.
There has been some attention given in the literature to the appropriateness of calculating relative metabolic rate by dividing resting metabolic rate by body weight or fat-free mass, since the line defining the relationship between these two variables does not intercept the y -axis at zero.
The results of this manipulation do reveal a decrease in resting metabolic rate due to diet alone and diet-plus-exercise. However, the slopes of the regression lines pre- and post-treatment are not significantly different, and, therefore, the relationship between mass and metabolic rate is the same and independent of treatment. In other words, the drop in resting metabolic rate is expected due to the decrease in body size.
The use of meta-analysis in this area of research is useful because it allows for a systematic examination of the many variables involved. It is, of course, limited by the range of studies available. In addition, the calorie level is rarely adjusted according to individual needs; therefore the actual calorie deficit per individual is an important confounding variable.
Based on the above reviews, we can revisit the controversial issues delineated in the introduction of this paper, and apply these issues to a family physician's practice.
One of the main points to be made is the potential impact of dietary intake, especially total calories, calorie deficits and grammes of protein per kilogram body weight. Further work is necessary to determine whether milder calorie deficits with adequate protein in combination with strength training can positively affect resting metabolic rate. In contrast to Kraemer and colleagues' work, the majority of the studies point to a reduction in short-term resting metabolic rates that is greater than can be explained by the loss of body mass or fat-free mass over the same time period.
Unfortunately, there has been very little work done over the last few years regarding the duration of this phenomenon. Wadden and colleagues' work indicates that this disproportionate reduction reflects metabolic processes associated with the hypocaloric dieting itself. There's no easy way to lose weight. The foundation for weight loss continues to be based on physical activity and diet.
Take in fewer calories than you burn, and you lose weight. The Dietary Guidelines for Americans recommends cutting calories by to calories a day to lose 1 to 1. If you can add some physical activity to your day, you'll accomplish your weight-loss goals even faster. There is a problem with information submitted for this request.
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Show references Anthanont P, et al. Does basal metabolic rate predict weight gain? The American Journal of Clinical Nutrition. Goldman L, et al. In: Goldman-Cecil Medicine. Philadelphia, Pa.
Accessed Aug. Working out with weights is a great strategy to keep your metabolism from slowing. Strength training has been shown to increase metabolic rate in healthy people, as well as those who have heart disease or are overweight or obese 28 , 29 , 30 , It increases muscle mass, which makes up much of the fat-free mass in your body.
Having a higher amount of fat-free mass significantly increases the number of calories you burn at rest 32 , 33 , In a 6-month study, people who performed strength training for 11 minutes per day, 3 days a week, experienced a 7.
In contrast, not doing any strength training can cause your metabolic rate to decline, especially during weight loss and aging 32 , 36 , Engaging in lifestyle behaviors that slow down your metabolism can lead to weight gain over time. That said, many simple activities can boost your metabolism to help you lose weight and keep it off. Your metabolism determines how many calories you burn each day. Here are 9 easy ways to boost your metabolism, backed by science.
Metabolic rates vary by individual. This article explains why some people have a fast metabolism and how you can speed up yours to burn more calories.
Coffee contains caffeine, a stimulant substance that is proven to increase the release of fats from the fat tissues and boost the resting metabolic…. What you eat affects your metabolism, making it either easier or harder to lose weight. Here are the 12 best foods to boost your metabolism. Your metabolism tends to slow with age, making it harder to lose weight. This article explains why your metabolism slows with age and what you can do. Junk foods are highly processed foods that tend to be high in calories but low in nutrients.
This article explores how junk food affects your…. The Fast Metabolism Diet is a nutrition program that promises to help you shed up to 20 pounds 9 kg in 28 days. This article reviews whether the…. Many supplements — including 7-Keto — claim to boost metabolism and aid weight loss. This article reviews whether 7-keto-DHEA supplements can improve…. Experts are…. Health Conditions Discover Plan Connect. Keeping your metabolism high is crucial for losing weight and keeping it off.
However, several common lifestyle mistakes may slow down your metabolism.
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