Effect of calorie restriction with or without exercise on insulin sensitivity, β-cell function, fat cell size, and ectopic lipid in overweight subjects

D. Enette Larson-Meyer, Leonie Heilbronn, Leanne M. Redman, Bradley R. Newcomer, Madlyn I. Frisard, Steve Anton, Steven R. Smith, Anthony Alfonso, Eric Ravussin

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359 Citations (Scopus)

Abstract

OBJECTIVE - The purpose of this article was to determine the relationships among total body fat, visceral adipose tissue (VAT), fat cell size (FCS), ectopic fat deposition in liver (intrahepatic lipid [IHL]) and muscle (intramyocellular lipid [IMCL]), and insulin sensitivity index (Si) in healthy overweight, glucose-tolerant subjects and the effects of calorie restriction by diet alone or in conjunction with exercise on these variables. RESEARCH DESIGN AND METHODS - Forty-eight overweight volunteers were randomly assigned to four groups: control (100% of energy requirements), 25% calorie restriction (CR), 12.5% calorie restriction +12.5% energy expenditure through structured exercise (CREX), or 15% weight loss by a low-calorie diet followed by weight maintenance for 6 months (LCD). Weight, percent body fat, VAT, IMCL, IHL, FCS, and Si were assessed at baseline and month 6. RESULTS - At baseline, FCS was related to VAT and IHL (P < 0.05) but not to IMCL. FCS was also the strongest determinant of Si (P < 0.01). Weight loss at month 6 was 1 ± 1% (control, mean ± SE), 10 ± 1% (CR), 10 ± 1% (CREX), and 14 ± 1% (LCD). VAT, FCS, percent body fat, and IHL were reduced in the three intervention groups (P < 0.01), but IMCL was unchanged. Si was increased at month 6 (P = 0.05) in the CREX (37 ± 18%) and LCD (70 ± 34%) groups (P < 0.05) and tended to increase in the CR group (40 ± 20%, P = 0.08). Together the improvements in Si were related to loss in weight, fat mass, and VAT, but not IHL, IMCL, or FCS. CONCLUSIONS - Large adipocytes lead to lipid deposition in visceral and hepatic tissues, promoting insulin resistance. Calorie restriction by diet alone or with exercise reverses this trend.

Original languageEnglish
Pages (from-to)1337-1344
Number of pages8
JournalDiabetes Care
Volume29
Issue number6
DOIs
Publication statusPublished or Issued - 2006

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism
  • Advanced and Specialised Nursing

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