Keith N. Frayn

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This paper reviews the assumptions involved in calculating rates of carbohydrate and fat oxidation from measurements of O2 consumption, CO2 production, and urinary nitrogen excretion. It is shown that erroneous results are obtained in the presence of metabolic processes such as lipogenesis and gluconeogenesis. The apparent rates calculated under these(More)
BACKGROUND Resistant starch may modulate insulin sensitivity, although the precise mechanism of this action is unknown. OBJECTIVE We studied the effects of resistant starch on insulin sensitivity and tissue metabolism. DESIGN We used a 4-wk supplementation period with 30 g resistant starch/d, compared with placebo, in 10 healthy subjects and assessed(More)
BACKGROUND A high fructose intake can lead to postprandial hypertriacylglycerolemia. The underlying mechanism is unclear. OBJECTIVE The objective of the study was to investigate the mechanisms involved in fructose-induced hypertriacylglycerolemia and the contribution of de novo lipogenesis in an acute setting. DESIGN In a randomized, crossover study, 14(More)
The glycaemic index (GI) concept was originally introduced to classify different sources of carbohydrate (CHO)-rich foods, usually having an energy content of >80 % from CHO, to their effect on post-meal glycaemia. It was assumed to apply to foods that primarily deliver available CHO, causing hyperglycaemia. Low-GI foods were classified as being digested(More)
BACKGROUND Adipose tissue macrophages (ATMs) have become a focus of attention recently because they have been shown to accumulate with an increase in fat mass and to be involved in the genesis of insulin resistance in obese mice. However, the phenotype and functions of human ATMs are still to be defined. METHODS AND RESULTS The present study, performed on(More)
Lipoprotein lipase (EC 3.1.1.34; LPL) is a key enzyme regulating the disposal of lipid fuels in the body. It is expressed in a number of peripheral tissues including adipose tissue, skeletal and cardiac muscle and mammary gland. Its role is to hydrolyse triacylglycerol (TG) circulating in the TG-rich lipoprotein particles in order to deliver fatty acids to(More)
British dietary recommendations are to decrease total fat intake to less than 30 % of daily energy intake and saturated fat to less than 10 %. In practice, it is difficult for people to make these changes. It may be easier to encourage people to switch from a diet rich in saturated fatty acids to one rich in polyunsaturated fatty acids. A total of 17(More)
There is a widespread acceptance in the literature that plasma nonesterified fatty acids (NEFA), also called free fatty acids (FFA), can mediate many adverse metabolic effects, most notably insulin resistance. Elevated NEFA concentrations in obesity are thought to arise from an increased adipose tissue mass. It is also argued that the process of fatty acid(More)
There is net outward flow of fatty acids from adipose tissue in the fasted state but net inward flow and storage in the postprandial state. We investigated how this is regulated. Arteriovenous differences were measured across a subcutaneous adipose depot in six normal subjects before and for 5 h after a meal containing 80 g fat and 80 g carbohydrate. In(More)
BACKGROUND High-carbohydrate (HC) diets increase de novo lipogenesis (DNL), but effects on stearoyl-CoA desaturase (SCD) are not so well studied. OBJECTIVE The objective was to investigate DNL and SCD in liver and adipose tissue by using fatty acid ratios after short-term dietary intervention. DESIGN Eight subjects consumed isoenergetic 3-d HC (10% fat;(More)