Journal Title (Medline/Pubmed accepted abbreviation): J. Strength and Conditioning Research
Page numbers: 51-60
doi (if applicable):
Summary of Background and Research Design
Background:Thermogenic products and meal replacement shakes are both popularly employed to achieve better body composition through fat loss and increased lean muscle mass. Thermogenic substances are compounds that increase metabolic rate, meaning that the body burns more calories while performing normal functions. Popular thermogenic products include caffeine, citrus aurantium, and epigallocatechin gallate (EGCG) from green tea. Meal replacement shakes are designed to offer vitamins and high amounts of protein that contribute to satiety and maintenance of lean body mass.
Hypothesis/Research Question:Compared to only an exercise routine and meal replacement shake, does a weight loss supplement (WLS) that contains thermogenic compounds have additional effects on body composition and fitness parameters in 8 wks in a group of overweight young adults?
Subjects:Sedentary, college-aged men and women, n = 24, 21.5 ± 4.5 yrs old
Experimental design:randomized, double-blind, placebo-controlled. Groups included 6 men and 6 women per group and subjects were matched for pre-treatment body weight. The experimental group was supplemented with a weight loss supplement (WLS) while the control group was administered a placebo.
Treatments and protocol:
Participants consumed 2 capsules/day of the WLS (or placebo), one in the morning and one midday with meals. All subjects consumed one meal replacement supplement/day and were encouraged to cut total caloric consumption. The WLS included lysine l-carnitine, citrus aurantium, 7-keto dehydroepiandrosterone, theobromine, caffeine, green tea extract, white willow bark, and dimethylethanolamine. The meal replacement supplement was Low Carb Ultramet® and included 220 kcal, 6.5 g total fat (4 g saturated fat), 6 g total carbohydrates (4 g sugar and 1.5 g dietary fiber), 35 g protein, and 25 vitamins and minerals.
All subjects participated in an exercise program that consisted of supervised resistance and cardiovascular exercise 3 days/wk for 8 wks.
Protocol: Before (T1) and after (T2) the 8 wk training protocol, subjects were evaluated for body mass, lean mass, fat mass, body fat percentage, blood pressure, serum clinical safety markers including total cholesterol and triglycerides, and fitness parameters including VO2max and 1RM bench press.
Summary of research findings:
No adverse effects were reported for any element of this protocol. Participants in both the placebo and the WLS group experienced a significant decrease in fat mass and body fat percentage in 8 wks, but there were no differences between groups. Significant increases in strength parameters were noted in both groups, specifically with bench press and leg press. Serum clinical safety markers were generally similar or slightly improved. Interestingly, fasting blood glucose levels decreased from 96.9 ± 10.7 mg/dL to 93.2 ± 5.6 mg/dL for the WLS group (P =0.22) while these levels increased from 89.5 ± 8.2 mg/dL to 92.9 ± 6.0 mg/dL for the placebo group (P =0.15). Although neither within group change was statistically significant, there was a significant group x treatment effect for fasting blood glucose (P = 0.048). A second notable marker was resting systolic blood pressure which decreased significantly for the WLS group (129.5 ± 11.1 mmHg at T1 to 115.7 ± 7.9 at T2, p=0.002) compared to the control group (124.5 ± 9.9 at T1 and 119.8 ± 6.1 at T2, P = 0.15). This equated to a nearly significant group x treatment effect (P =0.06).
Interpretation of findings/Key practice applications:
When practicing a weight loss routine with cardiovascular and resistance training and meal replacement supplements for 8 wks, there may not be a significant additional benefit with a thermogenic supplement. However, there were not any reported side effects in regard to health or clinical markers and this supplement.
Initial body weight and body composition data were not presented separately for males and females, but it appears from the mean overall body weights, heights, and percent body fat determinations displayed that the subjects were not significantly overweight. In addition, the subjects were not hypertensive. It would have been interesting to see if repeating this study in subjects with a greater degree of overweight would have had the same results.