Tags

Type your tag names separated by a space and hit enter

Different forms of obesity as a function of diet composition.
Int J Obes (Lond). 2005 Nov; 29(11):1368-78.IJ

Abstract

OBJECTIVE

To characterize the phenotype of obesity on a high-carbohydrate diet (HCD) as compared to a high-fat diet (HFD) or moderate-fat diet (MFD).

METHODS AND PROCEDURES

In four experiments, adult Sprague-Dawley rats (275-300 g) were maintained for several weeks on a: (1) HFD with 50% fat; (2) balanced MFD with 25% fat; or (3) HCD with 10% fat/65% carbohydrate. Then, based on the amount of body fat accumulated in four dissected fat pads, the animals were subgrouped as lean (lowest tertile) or obese (highest tertile) and characterized with multiple measures.

RESULTS

The obese rats of these diet groups, with 70-80% greater body fat than the lean animals, exhibited elevated levels of leptin and insulin and increased activity of lipoprotein lipase in adipose tissue (aLPL), with no change in muscle LPL. Characteristics common to the obese rats on the HFD or MFD, but not seen on the HCD, were hyperphagia, elevated circulating levels of triglycerides (TG), nonesterified fatty acids (NEFA) and glucose, and a significant increase in beta-hydroxyacyl-CoA dehydrogenase (HADH) activity in muscle, reflecting its greater capacity to metabolize fat. This was accompanied by a significant increase in expression of the peptide, galanin (GAL), in the paraventricular nucleus (PVN), as measured by in situ hybridization and real-time quantitative PCR, and also in GAL peptide immunoreactivity. These measures of GAL were consistently, positively correlated with circulating TG levels and also with HADH activity in muscle. In contrast to these fat-associated changes, rats that became obese on an HCD maintained normal caloric intake and levels of TG, NEFA, and glucose. They also showed no change in PVN GAL mRNA or peptide. Instead, they exhibited a significant reduction in HADH activity compared to the lean animals, along with increased activity of phosphofructokinase in muscle, a key enzyme in glycolysis.

CONCLUSION

Specific characteristics of obesity, including expression of hypothalamic peptides, are dependent upon diet composition. Whereas obesity on an HFD is associated with hyperphagia and elevated lipids, fat metabolism in muscle, and fat-stimulated peptides such as GAL, obesity on an HCD with a similar increase in body fat shows none of these characteristics and instead exhibits a metabolic pattern in muscle that favors carbohydrate over fat oxidation. These results suggest the existence of multiple forms of obesity with different underlying mechanisms that are diet dependent.

Authors+Show Affiliations

The Rockefeller University, New York, NY 10021, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

16088331

Citation

Dourmashkin, J T., et al. "Different Forms of Obesity as a Function of Diet Composition." International Journal of Obesity (2005), vol. 29, no. 11, 2005, pp. 1368-78.
Dourmashkin JT, Chang GQ, Gayles EC, et al. Different forms of obesity as a function of diet composition. Int J Obes (Lond). 2005;29(11):1368-78.
Dourmashkin, J. T., Chang, G. Q., Gayles, E. C., Hill, J. O., Fried, S. K., Julien, C., & Leibowitz, S. F. (2005). Different forms of obesity as a function of diet composition. International Journal of Obesity (2005), 29(11), 1368-78.
Dourmashkin JT, et al. Different Forms of Obesity as a Function of Diet Composition. Int J Obes (Lond). 2005;29(11):1368-78. PubMed PMID: 16088331.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Different forms of obesity as a function of diet composition. AU - Dourmashkin,J T, AU - Chang,G-Q, AU - Gayles,E C, AU - Hill,J O, AU - Fried,S K, AU - Julien,C, AU - Leibowitz,S F, PY - 2005/8/10/pubmed PY - 2006/3/29/medline PY - 2005/8/10/entrez SP - 1368 EP - 78 JF - International journal of obesity (2005) JO - Int J Obes (Lond) VL - 29 IS - 11 N2 - OBJECTIVE: To characterize the phenotype of obesity on a high-carbohydrate diet (HCD) as compared to a high-fat diet (HFD) or moderate-fat diet (MFD). METHODS AND PROCEDURES: In four experiments, adult Sprague-Dawley rats (275-300 g) were maintained for several weeks on a: (1) HFD with 50% fat; (2) balanced MFD with 25% fat; or (3) HCD with 10% fat/65% carbohydrate. Then, based on the amount of body fat accumulated in four dissected fat pads, the animals were subgrouped as lean (lowest tertile) or obese (highest tertile) and characterized with multiple measures. RESULTS: The obese rats of these diet groups, with 70-80% greater body fat than the lean animals, exhibited elevated levels of leptin and insulin and increased activity of lipoprotein lipase in adipose tissue (aLPL), with no change in muscle LPL. Characteristics common to the obese rats on the HFD or MFD, but not seen on the HCD, were hyperphagia, elevated circulating levels of triglycerides (TG), nonesterified fatty acids (NEFA) and glucose, and a significant increase in beta-hydroxyacyl-CoA dehydrogenase (HADH) activity in muscle, reflecting its greater capacity to metabolize fat. This was accompanied by a significant increase in expression of the peptide, galanin (GAL), in the paraventricular nucleus (PVN), as measured by in situ hybridization and real-time quantitative PCR, and also in GAL peptide immunoreactivity. These measures of GAL were consistently, positively correlated with circulating TG levels and also with HADH activity in muscle. In contrast to these fat-associated changes, rats that became obese on an HCD maintained normal caloric intake and levels of TG, NEFA, and glucose. They also showed no change in PVN GAL mRNA or peptide. Instead, they exhibited a significant reduction in HADH activity compared to the lean animals, along with increased activity of phosphofructokinase in muscle, a key enzyme in glycolysis. CONCLUSION: Specific characteristics of obesity, including expression of hypothalamic peptides, are dependent upon diet composition. Whereas obesity on an HFD is associated with hyperphagia and elevated lipids, fat metabolism in muscle, and fat-stimulated peptides such as GAL, obesity on an HCD with a similar increase in body fat shows none of these characteristics and instead exhibits a metabolic pattern in muscle that favors carbohydrate over fat oxidation. These results suggest the existence of multiple forms of obesity with different underlying mechanisms that are diet dependent. SN - 0307-0565 UR - https://www.unboundmedicine.com/medline/citation/16088331/Different_forms_of_obesity_as_a_function_of_diet_composition_ L2 - http://dx.doi.org/10.1038/sj.ijo.0803017 DB - PRIME DP - Unbound Medicine ER -