Monday, April 27, 2009

Performance Research for April : Fat Loss and Exercise part 2

More studies than you can shake a stick at! As always, see my notes below each one.

Bring it!

Effects of Exercise Training Intensity on Nocturnal Growth Hormone Secretion in Obese Adults with the Metabolic Syndrome.

Irving BA, Weltman JY, Patrie JT, Davis CK, Brock DW, Swift D, Barrett EJ, Gaesser GA, Weltman A. Departments of Human Services, Internal Medicine, Division of Endocrinology and Metabolism, Pediatrics, Division of Cardiovascular Medicine, Health Evaluation Sciences, General Clinical Research Center, Center for the Study of Complementary and Alternative Therapies, University of Virginia, Charlottesville, Virginia 22908.

Context: Abdominal adiposity is associated with reduced spontaneous growth hormone (GH) secretion and increased incidence of the metabolic syndrome, type 2 diabetes, and cardiovascular disease. Exercise training increases GH secretion, induces abdominal visceral fat (AVF) loss and has been shown to improve the cardiometabolic risk factor profile. However, little is known about the effects of endurance training intensity on spontaneous GH release in obese individuals.

Objective: To examine the effects of sixteen weeks of endurance training on spontaneous 12-h overnight GH secretion in adults with the metabolic syndrome. Design and Setting: This randomized, controlled exercise intervention was conducted at the University of Virginia. Participants: Thirty-four adults with the metabolic syndrome (mean+/-SEM: Age: 49.1+/-1.8 years) participated.

Intervention: Subjects were randomized to one of three groups for 16 weeks: no-exercise training (Control), low-intensity exercise training (LIET), or high-intensity training (HIET).

Main Outcome Measure: Change in nocturnal integrated GH area under the curve (AUC). Results: Both exercise training conditions augmented within-group nocturnal GH AUC pre- to post-training [LIET approximately upward arrow49%, p<0.05 r =" -0.34," p="0.051," n="34)," r =" 0.02," p="0.920," n="34)." style="font-weight: bold;">

CONCLUSION: Sixteen weeks of supervised exercise training in adults with the metabolic syndrome increases spontaneous nocturnal growth hormone secretion independent of exercise training intensity.

My Notes: 1) Don't get Metabolic Syndrome---it screws up all sorts of things, and add GH to the list 2) ANY exercise will start to push you back towards "health" 3) GH was better, although it did not change the fat levels. This does not mean it has no effect, it just did not have an effect under these conditions.

Effects of Exercise and Low-Fat Diet on Adipose Tissue Inflammation and Metabolic Complications in Obese Mice.

Vieira VJ, Valentine RJ, Wilund KR, Antao N, Baynard T, Woods JA. UNIVERSITY OF ILLINOIS.

Adipose tissue inflammation causes metabolic disturbances including insulin resistance and hepatic steatosis. Exercise training (EX) may decrease adipose tissue inflammation thereby ameliorating such disturbances, even in the absence of fat loss. The purpose of this study was to 1) compare the effects of low-fat diet (LFD), EX, and their combination on inflammation, insulin resistance, and hepatic steatosis in high-fat diet-induced obese mice and, 2) determine the effect of intervention duration (i.e. 6 vs. 12 wks). C57BL/6 mice (n=109) fed a 45% fat diet (HFD) for 6 wks were randomly assigned to an EX (treadmill, 5d/wk; 6 or 12 wks; 40 min/d; 65-70%VO2max) or sedentary (SED) group. Mice remained on HFD or were placed on a 10% fat diet (LFD) for 6 or 12 wks.

Following interventions, fat pads were weighed and expressed relative to body weight; hepatic steatosis was assessed by total liver triglyceride; insulin resistance by HOMA-IR and Glucose AUC. Rt-PCR was used to determine adipose gene expression of MCP-1, F4/80, TNF-alpha, and leptin. By 12 wks, MCP-1, F4/80, and TNF-alpha mRNA were reduced by EX and LFD. Exercise (p=0.02), adiposity (p=0.03), and adipose F4/80 (p=0.02) predicted reductions in HOMA-IR (R(2)=.75; p<0.001); p="0.04)" style="font-weight: bold;">

CONCLUSION: There are unique metabolic consequences of a sedentary lifestyle and fat high diet that are most evident long-term, highlighting the importance of both Exercise training and low-fat diet in preventing obesity-related metabolic disturbances.

My notes: Ok, this one is starting to piss me off. Why was it the high fat? The TYPE of fat will have a radical effect on the results and the amount of carbohydrates in the diet may also alter the way fats are used; as Jeff Volek's lab have shown that saturated fats (which again are not all equal) in a LOW carbohydrate environment don't seem to alter lipid levels.

Enough with the rat/mice studies already! Why was this done in mice? I know they are easier to study than those pesky humans (trust me, I've done human studies and anyone who has can attest to that the "pain in the butt factor" is MUCH higher), but we need more HUMAN data on this type of stuff.
The good part is that exercise once again helps! Get your hand out of the cheese doodles bag and off the couch!

Influence of sex on total and regional fat loss in overweight and obese men and women.

Kuk JL, Ross R. 1School of Kinesiology and Health Science, Faculty of Health Science, York University, Toronto, Ontario, Canada.

Objective:To determine the influence of sex on the association between reductions in body weight (BW) and waist circumference (WC) with reductions in total (TAT), subcutaneous (SAT) and visceral adipose tissue (VAT) in response to lifestyle-based interventions.Design: Changes in TAT, SAT and VAT were assessed using magnetic resonance imaging in 81 men and 72 women who had participated in various diet and/or exercise interventions at Queen's University, Ontario, Canada.

Results:Reductions in BW and WC were significantly (P<0.001)>0.05). Reductions in BW and WC were both independent predictors of VAT loss.

CONCLUSION: These observations suggest that for a given reduction in body weight or waist circumference, men lose more visceral adipose tissue and less subcutaneous than women; however, the total loss observed for a given reduction in body weight or waist circumference in men and women is not different.

My Notes: I know you were hoping that this study was about how much sex you have and weight loss, so sorry to disappoint you. It does show that even the AMOUNT of weight lost, men and women can loose it from different areas. Nothing earth shattering there.

Moderate Exercise Attenuates the Loss of Skeletal Muscle Mass That Occurs With Intentional Caloric Restriction-Induced Weight Loss in Older, Overweight to Obese Adults.

Chomentowski P, Dubé JJ, Amati F, Stefanovic-Racic M, Zhu S, Toledo FG, Goodpaster BH. Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, N810 Montefiore Hospital, 3459 Fifth Avenue, Pittsburgh, PA 15213.

BACKGROUND: Aging is associated with a loss of muscle mass and increased body fat. The effects of diet-induced weight loss on muscle mass in older adults are not clear. Purpose This study examined the effects of diet-induced weight loss, alone and in combination with moderate aerobic exercise, on skeletal muscle mass in older adults. METHODS: Twenty-nine overweight to obese (body mass index = 31.8 +/- 3.3 kg/m(2)) older (67.2 +/- 4.2 years) men (n = 13) and women (n = 16) completed a 4-month intervention consisting of diet-induced weight loss alone (WL; n = 11) or with exercise (WL/EX; n = 18). The WL intervention consisted of a low-fat, 500-1,000 kcal/d caloric restriction. The WL/EX intervention included the WL intervention with the addition of aerobic exercise, moderate-intensity walking, three to five times per week for 35-45 minutes per session. Whole-body dual-energy x-ray absorptiometry, thigh computed tomography (CT), and percutaneous muscle biopsy were performed to assess changes in skeletal muscle mass at the whole-body, regional, and cellular level, respectively.

RESULTS: Mixed analysis of variance demonstrated that both groups had similar decreases in bodyweight (WL, -9.2% +/- 1.0%; WL/EX, -9.1% +/- 1.0%) and whole-body fat mass (WL, -16.5%, WL/EX, -20.7%). However, whole-body fat-free mass decreased significantly (p < .05) in WL (-4.3% +/- 1.2%) but not in WL/EX (-1.1% +/- 1.0%). Thigh muscle cross-sectional area by CT decreased in both groups (WL, -5.2% +/- 1.1%; WL/EX, -3.0% +/- 1.0%) and was not statistically different between groups. Type I muscle fiber area decreased in WL (-19.2% +/- 7.9%, p = .01) but remained unchanged in WL/EX (3.4% +/- 7.5%). Similar patterns were observed in type II fibers (WL, -16.6% +/- 4.0%; WL/EX, -0.2% +/- 6.5%).

CONCLUSION: Diet-induced weight loss significantly decreased muscle mass in older adults. However, the addition of moderate aerobic exercise to intentional weight loss attenuated the loss of muscle mass.

My Notes: When you are on a "diet" to drop some fat, don't just cut your calories and hop on the treadmill till you puke. You need to do something to tell your body to keep the muscle you have, as that is what keeps your metabolic rate in tact long term. This study provides data showing that even moderate aerobic exercise (think "cardio") was better than nothing. Although it was not studied here, I would bet that strength training would be even better at keeping muscle in this study (and there are data to support that notion).

Effect of dietary adherence with or without exercise on weight loss: a mechanistic approach to a global problem.

Del Corral P, Chandler-Laney PC, Casazza K, Gower BA, Hunter GR. Department of Nutrition Science, Clinical Nutrition Research Unit; Department of Human Studies, University of Alabama at Birmingham.

Context: Weight loss using low calorie diets produce variable results, presumably due to a wide range of energy deficits and low dietary adherence. Objective: To quantify the relationship between dietary adherence, weight loss and severity of caloric restriction. Design and Setting: Participants were randomized to diet-only, diet-endurance-training, or diet-resistance-training until (60-539 days) BMI <25 n="141)" r=" -" r=" -0.349" r="0.364," r=" -0.387," style="font-weight: bold;">

CONCLUSION: Dietary adherence is strongly associated with rates of weight loss and adversely affected by the severity of caloric restriction. Weight loss programs should consider moderate caloric restriction relative to estimates of energy requirements, rather than generic low calorie diets.

My Notes: Um, yeah. The best "diet" (hate that word) in the world makes no difference if you do NOT follow it!

Rock on
Mike T Nelson