Exposure of 7-week-old normal rats for 3-7 months to a diet deprived of long-chain polyunsaturated ω3 fatty acids was recently reported to induce changes in the fatty acid content and pattern of liver phospholipids and triglycerides similar to those otherwise found in second generation ω3-depleted rats. In the present study, the changes in body weight, parametrial adipose tissue mass, plasma glucose and insulin concentrations and insulin resistance index were investigated in the same control and ω3-depleted rats, which were then given access for 2 to 4-5 weeks to either a flaxseed oil-enriched diet (control and ω3-depleted rats) or a soybean oil-enriched diet (control rats). The body weight failed to differ between control and ω3-depleted rats. The latter rats, however, displayed increases in adipose tissue mass, plasma glucose and insulin concentrations, and insulin resistance index. In the control rats given access to the soybean or flaxseed oil-enriched diet, body weight and adipose tissue mass were little affected, but both the plasma glucose concentration and insulin resistance index decreased. In the ω3-depleted rats given access to the flaxseed oil-enriched diet, both body weight and adipose tissue mass underwent a rapid, pronounced and sustained increase, whilst the plasma glucose concentration and insulin resistance index decreased similarly to those in the control rats. The present design of ω3 fatty acid dietary deprivation thus reproduces the visceral obesity and insulin resistance otherwise observed in second-generation ω3-depleted rats. However, the supply of exogenous ω3 fatty acids to the ω3-depleted rats failed to oppose visceral obesity, possibly as a result of the orexigenic effects of these ω3 fatty acids.

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