Exercise and the Institute of Medicine Recommendations for Nutrition

Effects of the Dietary Approaches to Stop Hypertension (DASH) Eating Plan on the Metabolic Side Effects of Corticosteroid Medications

OBJECTIVE

We aimed to determine the effects of the Dietary Approaches to Stop Hypertension (DASH) diet on the metabolic side effects of corticosteroid medication use.

DESIGN

A randomized clinical trial was undertaken in 60 patients on corticosteroid therapy for 10 weeks. Patients were randomly assigned to a DASH or control diet. Carbohydrate, protein, and fat in both groups were 50-60%, 15-20%, 30%, respectively. DASH diet was a diet rich in fruits, vegetables, whole grains, low-fat dairy products, and low in total and saturated fat and cholesterol, refined grains, and also sweets. Fasting blood samples were collected to determine blood glucose and lipid profile. Blood pressure and anthropometric measurements were measured based on the standard guidelines.

RESULTS

The mean age and body mass index (BMI) were 31.1 ± 3.6 year and 26.9 ± 2.6 kg/m(2), respectively. There were no significant differences between age and BMI in two groups at baseline. No significant difference was observed in body weight and waist circumference following the DASH diet compared to control diet. Systolic and diastolic blood pressures were significantly different following the DASH eating pattern (P = 0.04). Serum total cholesterol and fasting blood glucose significantly decreased in those following the DASH diet after adjustment for potential confounders.

CONCLUSION

The DASH diet had beneficial effects on several metabolic side effects among patients using corticosteroid medications.

Day to day variability in fat oxidation and the effect after only 1 day of change in diet composition

Indirect calorimetry is a common and noninvasive method to estimate rate of fat oxidation (FatOx) during exercise, and test-retest reliability should be considered when interpreting results. Diet also has an impact on FatOx. The aim of the present study was to investigate day to day variations in FatOx during moderate exercise given the same diet and 2 different isoenergetic diets. Nine healthy, moderately-trained females participated in the study. They performed 1 maximal oxygen uptake test and 4 FatOx tests. Habitual diets were recorded and repeated to assess day to day variability in FatOx. FatOx was also measured after 1 day of fat-rich (26.8% carbohydrates (CHO), 23.2% protein, 47.1% fat) and 1 day of CHO-rich diet (62.6% CHO, 20.1% protein, 12.4% fat). The reliability test revealed no differences in FatOx, respiratory exchange ratio (RER), oxygen uptake, carbon dioxide production, heart rate, blood lactate concentration, or blood glucose between the 2 habitual diet days. FatOx decreased after the CHO-rich diet compared with the habitual day 2 (from 0.42 ± 0.15 to 0.29 ± 0.13 g·min(-1), p < 0.05). No difference was found in FatOx between fat-rich diet and the 2 habitual diet days. FatOx was 31% lower (from 0.42 ± 0.14 to 0.29 ± 0.13 g·min(-1), p < 0.01) after the CHO-rich diet compared with the fat-rich diet. Using RER data to measure FatOx is a reliable method as long as the diet is strictly controlled. However, even a 1-day change in macronutrient composition will likely affect the FatOx results.

Retrospective Analysis of Protein- and Carbohydrate-Focused Diets Combined with Exercise on Metabolic Syndrome Prevalence in Overweight and Obese Women

BACKGROUND

To examine the effect of protein-focused (PRO, 1.14 g/kg/day) and carbohydrate-focused (CHO, ∼2.2 g/kg/day) diets (∼1600 kcals) combined with 10 weeks of circuit exercise training in sedentary overweight/obese women (N = 661, age 46 ± 11 years) on metabolic syndrome (MetS).

METHODS

We retrospectively analyzed eight exercise training studies performed from 2002-2014. Primary (MetS), secondary (MetS z-scores and individual MetS components), and tertiary outcomes [body mass index (BMI) by WHO cut points] were analyzed using chi-square, GLM, and McNemar's tests.

RESULTS

Both groups experienced significant weight loss, improvements in fitness, and reductions in MetS prevalence from baseline to follow-up (PRO: 49% to 42%, CHO: 42% to 36%, both P < 0.01). MetS z-score improvement (∼66.5%) was similar for both groups with no significant between-group differences noted. There were also no significant differences for individual component features between groups for the following: waist circumference (-0.28 ± 0.02 vs. -0.28 ± 0.025 cm, P = 0.97), glucose (-0.07 ± 0.03 vs. -0.08 ± 0.04 mM, P = 0.87), triglycerides (-0.16 ± 0.04 vs. -0.09 ± 0.04 mM, P = 0.20), high-density lipoprotein cholesterol (-0.21 ± 0.03 vs. -0.19 ± 0.04 mM, P = 0.68), and systolic BP (-0.16 ± 0.4 vs. -0.24 ± 0.05 mmHg, P = 0.26). Diastolic BP showed a minor advantage for the PRO group (-0.14 ± 0.05 vs. -0.30 ± 0.05 mmHg P = 0.02). When stratified by BMI, those with morbid obesity did not show a significant improvement in MetS while following a PRO-focused diet; however, caution is warranted given the exploratory nature of this analysis.

CONCLUSIONS

Our findings suggest that a low-moderate calorie diet partitioned for CHO and PRO preference is equally effective when combined with a structured exercise program for reducing the prevalence of MetS prevalence in overweight/obese women.

Positive effect of mushrooms substituted for meat on body weight, body composition, and health parameters. A 1-year randomized clinical trial

Reducing energy density (ED) of the diet is an important strategy for controlling obesity. This 1-year, randomized clinical trial examined the effect of substituting mushrooms for red meat ('mushroom diet'), compared to a standard diet ('meat diet'), on weight loss and maintenance among 73 obese adults (64 women, 9 men). The subjects completed anthropometric measurements and 7-day food records four times during a standardized weight loss and maintenance regimen. At the end of the 1-year trial, compared to participants on the standard diet, participants on the mushroom diet (n=36) reported lower intakes of energy (mean ± [SE]=-123 ± 113 kcals) and fat (-4.25 ± 6.88 g), lost more pounds and percentage body weight (-7.03 ± 3.34 lbs, 3.6%), achieved lower body mass index (-1.53 ± 0.36), waist circumference (-2.6 ± 3.5 in.) and percent total body fat (-0.85 ± 0.53), and had lower systolic and diastolic pressure (-7.9 and -2.5 mmHg); their lipid profile and inflammatory markers also improved. After initial weight loss, subjects following the mushroom diet maintained that loss well. Those who completed the full 12-month trial still weighed a mean of 7 lbs less than baseline. Thus, encouraging adults to substitute mushrooms for red meat was a useful strategy for enhancing weight loss, weight maintenance, and health parameters.

Physiological and nutritional aspects of post-exercise recovery: specific recommendations for female athletes

Gender-based differences in the physiological response to exercise have been studied extensively for the last four decades, and yet the study of post-exercise, gender-specific recovery has only been developing in more recent years. This review of the literature aims to present the current state of knowledge in this field, focusing on some of the most pertinent aspects of physiological recovery in female athletes and how metabolic, thermoregulatory, or inflammation and repair processes may differ from those observed in male athletes. Scientific investigations on the effect of gender on substrate utilization during exercise have yielded conflicting results. Factors contributing to the lack of agreement between studies include differences in subject dietary or training status, exercise intensity or duration, as well as the variations in ovarian hormone concentrations between different menstrual cycle phases in female subjects, as all are known to affect substrate metabolism during sub-maximal exercise. If greater fatty acid mobilization occurs in females during prolonged exercise compared with males, the inverse is observed during the recovery phase. This could explain why, despite mobilizing lipids to a greater extent than males during exercise, females lose less fat mass than their male counterparts over the course of a physical training programme. Where nutritional strategies are concerned, no difference appears between males and females in their capacity to replenish glycogen stores; optimal timing for carbohydrate intake does not differ between genders, and athletes must consume carbohydrates as soon as possible after exercise in order to maximize glycogen store repletion. While lipid intake should be limited in the immediate post-exercise period in order to favour carbohydrate and protein intake, in the scope of the athlete's general diet, lipid intake should be maintained at an adequate level (30%). This is particularly important for females specializing in long-duration events. With protein balance, it has been shown that a negative nitrogen balance is more often observed in female athletes than in male athletes. It is therefore especially important to ensure that this remains the case during periods of caloric restriction, especially when working with female athletes showing a tendency to limit their caloric intake on a daily basis. In the post-exercise period, females display lower thermolytic capacities than males. Therefore, the use of cooling recovery methods following exercise, such as cold water immersion or the use of a cooling vest, appear particularly beneficial for female athletes. In addition, a greater decrease in arterial blood pressure is observed after exercise in females than in males. Given that the return to homeostasis after a brief intense exercise appears linked to maintaining good venous return, it is conceivable that female athletes would find a greater advantage to active recovery modes than males. This article reviews some of the major gender differences in the metabolic, inflammatory and thermoregulatory response to exercise and its subsequent recovery. Particular attention is given to the identification of which recovery strategies may be the most pertinent to the design of training programmes for athletic females, in order to optimize the physiological adaptations sought for improving performance and maintaining health.

Influence of exercise on nutritional requirements

There is no consensus on the best diet for exercise, as many variables influence it. We propose an approach that is based on the total energy expenditure of exercise and the specific macro- and micronutrients used. di Prampero quantified the impact of intensity and duration on the energy cost of exercise. This can be used to determine the total energy needs and the balance of fats and carbohydrates (CHO). There are metabolic differences between sedentary and trained persons, thus the total energy intake to prevent overfeeding of sedentary persons and underfeeding athletes is important. During submaximal sustained exercise, fat oxidation (FO) plays an important role. This role is diminished and CHO's role increases as exercise intensity increases. At super-maximal exercise intensities, anaerobic glycolysis dominates. In the case of protein and micronutrients, specific recommendations are required. We propose that for submaximal exercise, the balance of CHO and fat favors fat for longer exercise and CHO for shorter exercise, while always maintaining the minimal requirements of each (CHO: 40% and fat: 30%). A case for higher protein (above 15%) as well as creatine supplementation for resistance exercise has been proposed. One may also consider increasing bicarbonate intake for exercise that relies on anaerobic glycolysis, whereas there appears to be little support for antioxidant supplementation. Insuring minimal levels of substrate will prevent exercise intolerance, while increasing some components may increase exercise tolerance.

Nutritional aspects of women strength athletes

Strength training elicits sports related and health benefits for both men and women. Although sexual dimorphism is observed in exercise metabolism, there is little information outlining the specific nutritional needs of women strength athletes. Many women athletes restrict energy intake, specifically fat consumption, in order to modify body composition, but this nutritional practice is often counter-productive. Compared to men, women appear to be less reliant on glycogen during exercise and less responsive to carbohydrate mediated glycogen synthesis during recovery. Female strength athletes may require more protein than their sedentary and endurance training counterparts to attain positive nitrogen balance and promote protein synthesis. Therefore, women strength athletes should put less emphasis on a very high carbohydrate intake and more emphasis on quality protein and fat consumption in the context of energy balance to enhance adaptations to training and improve general health. Attention to timing of nutrient ingestion, macronutrient quality, and dietary supplementation (for example, creatine) are briefly discussed as important components of a nutritionally adequate and effective strength training diet for women.