Abstract
PurposeHigh-fat, high-calorie (HFHC) diets have been used as a model to investigate lipid-induced insulin resistance. Short-term HFHC diets reduce insulin sensitivity in young healthy males, but to date, no study has directly compared males and females to elucidate sex-specific differences in the effects of a HFHC diet on functional metabolic and cardiovascular outcomes.MethodsEleven males (24 ± 4 years; BMI 23 ± 2 kg.m−2; V̇O2 peak 62.3 ± 8.7 ml.min−1.kg−1FFM) were matched to 10 females (25 ± 4 years; BMI 23 ± 2 kg.m−2; V̇O2 peak 58.2 ± 8.2 ml.min−1.kg−1FFM). Insulin sensitivity, measured via oral glucose tolerance test, metabolic flexibility, arterial stiffness, body composition and blood lipids and liver enzymes were measured before and after 7 days of a high-fat (65% energy) high-calorie (+ 50% kcal) diet.ResultsThe HFHC diet did not change measures of insulin sensitivity, metabolic flexibility or arterial stiffness in either sex. There was a trend towards increased total body fat mass (kg) after the HFHC diet (+ 1.8% and + 2.3% for males and females, respectively; P = 0.056). In contrast to females, males had a significant increase in trunk to leg fat mass ratio (+ 5.1%; P = 0.005).ConclusionLean, healthy young males and females appear to be protected from the negative cardio-metabolic effects of a 7-day HFHC diet. Future research should use a prolonged positive energy balance achieved via increased energy intake and reduced energy expenditure to exacerbate negative metabolic and cardiovascular functional outcomes to determine whether sex-specific differences exist under more metabolically challenging conditions.
Highlights
A western lifestyle is characterised by regular consumption of readily available energy-dense foods [1], often paired with sedentary behaviour throughout the day [2] and/or minimal amounts of exercise [3]
A cohort of young healthy males (n = 11) and females (n = 11) were matched for BMI, age and VO2 peak [ml.min−1.kg (fat-free mass (FFM))−1]. VO2 peak was adjusted to FFM to remove the influence of increased fat mass on body mass observed in the female cohort allowing for direct comparison of sexes
All participants adhered to the HFHC diet and any food that was not consumed by the participants was notified to the researchers and returned to the laboratory to allow HFHC diet calculations to be adjusted
Summary
A western lifestyle is characterised by regular consumption of readily available energy-dense foods [1], often paired with sedentary behaviour throughout the day [2] and/or minimal amounts of exercise [3]. These behavioural patterns are associated with an increased risk of obesity, type 2 diabetes (T2D) and cardiovascular disease [4,5,6]. Insulin resistance is defined as impaired insulin-stimulated glucose uptake in skeletal muscle and adipose tissue stores often combined with impaired insulin-induced suppression of hepatic glucose production. Metabolic flexibility is often diminished in obese insulin-resistant individuals in comparison to the lean insulin-sensitive state [13]
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