Increased adipose tissue lipolysis after a 2-week high-fat diet in sedentary overweight/obese men

Abstract

The purpose of this study was to determine if a high-fat diet would result in a higher lipolytic rate in subcutaneous adipose tissue than a lower-fat diet in sedentary nonlean men. Six participants (healthy males; 18-40 years old; body mass index, 25-37 kg/m(2)) underwent 2 weeks on a high-fat or well-balanced diet of similar energy content (approximately 6695 kJ) in randomized order with a 10-day washout period between diets. Subcutaneous abdominal adipose tissue lipolysis was determined over the course of a day using microdialysis after both 2-week diet sessions. Average interstitial glycerol concentrations (index of lipolysis) as determined using microdialysis were higher after the high-fat diet (210.8 ± 27.9 μmol/L) than after a well-balanced diet (175.6 ± 23.3 μmol/L; P = .026). There was no difference in adipose tissue microvascular blood flow as determined using the microdialysis ethanol technique. These results demonstrate that healthy nonlean men who diet on the high-fat plan have a higher lipolytic rate in subcutaneous abdominal adipose tissue than when they diet on a well-balanced diet plan. This higher rate of lipolysis may result in a higher rate of fat mass loss on the high-fat diet; however, it remains to be determined if this higher lipolytic rate in men on the high-fat diet results in a more rapid net loss of triglyceride from the abdominal adipose depots, or if the higher lipolytic rate is counteracted by an increased rate of lipid storage.

Figure 1

Comparison between participants’ dialysate (nearly equal to interstitial) glycerol concentrations when on the high-fat or Well-Balanced diets. Data are presented as a 24-hour average (overall average), during eating (eating average), and during sedentary periods (sedentary average). Microdialysis probes were placed in the abdominal subcutaneous adipose tissue and perfused at 0.3 μl/min. N= 6,6,6 (* P <0.05; different from well-balanced).

Figure 2

Comparison between participants’ dialysate glycerol concentrations when on the High-fat or Well-Balanced diets. Data are presented as a 24-hour average (overall average), during eating (eating average), and during sedentary periods (sedentary average). Microdialysis probes were placed in the abdominal subcutaneous adipose tissue and perfused at 2.0 μl/min. N= 6,6,6 (* P <0.05; different from well-balanced).

Figure 3

Comparison between participants’ overall interstitial glycerol concentrations over time when on the high-fat and well-Balanced diets. Dialysate samples were collected every hour from microdialysis probes perfused at 0.3 ul/min and placed in subcutaneous abdominal adipose tissue in non-lean adult males. The first sample was collected the first morning in a fasted state. The second-to-last sample was collected during the overnight period. The final sample was collected the following morning in a fasted state. P = 0.026. N=6,6