Dr Adam Collins

The intermittent energy restriction (IER) approach to weight-loss involves short periods of substantial (>70%) energy restriction interspersed with normal eating. Studies to date comparing IER to continuous energy restriction (CER) have predominantly measured fasting indices of cardiometabolic risk. This study aimed to compare the effects of IER and CER on postprandial glucose and lipid metabolism following matched weight-loss. 27 (13 male) overweight/obese participants (46±3y, 30.1±1.0kg/m2) were randomised to either an IER (2638 kJ for two days/week with an overall ER of 22±0.3%, n=15) or CER (2510kJ below requirements with overall ER of 23±0.8%) intervention. Six-hour postprandial responses to a test meal and changes in anthropometry (fat mass, fat-free mass, circumferences) were assessed at baseline and upon attainment of 5% weight-loss, following a 7 day period of weight stabilisation. The study found no significant difference in the time to attain a 5% weight loss between groups (median 59 [41-70] days and 73 [48-128] days respectively, p=0.246), or in body composition (p≥0.430). For postprandial measures, neither diet significantly altered glycaemia (p=0.226), whereas insulinaemia was reduced comparatively (p=0.903). The reduction in c-peptide tended (p=0.057) to be greater following IER (309128±23268 to 247781±20709 pmol.360min.L-1) versus CER (297204±25112 to 301655±32714 pmol.360min.L-1). The relative reduction in triacylglycerol responses was greater (p=0.045) following IER (106±30 to 68±15 mmol.360min.L-1) compared to CER (117±43 to 130±31 mmol.360min.L-1). In conclusion, these preliminary findings highlight underlying differences between IER and CER, including a superiority of IER in reducing postprandial lipaemia, which now warrant targeted mechanistic evaluation within larger study cohorts.

Exercise is capable of influencing the regulation of energy balance by acutely modulating appetite and energy intake coupled to effects on substrate utilization. Yet, few studies have examined acute effects of exercise intensity on aspects of both energy intake and energy metabolism, independently of energy cost of exercise. Furthermore, little is known as to the gender differences of these effect. One hour after a standardised breakfast, 40 (19 female), healthy participants (BMI 23.6±3.6 kg.m-2, VO2peak 34.4±6.8 ml.min-1.min-1) undertook either High intensity intermittent cycling consisting of 8 repeated 60s bouts of cycling at 95% VO2peak (HIIC) or low intensity continuous cycling, equivalent to 50% VO2peak (LICC), matched for energy cost (~950kJ) followed by 90mins of rest, in a randomised crossover design. Throughout each study visit satiety was assessed subjectively using visual analogue scales alongside blood metabolites and GLP-1. Energy expenditure and substrate utilization were measured over 75 minutes post-exercise via indirect calorimetry. Energy intake was assessed for 48hours post-intervention. No differences in appetite, GLP-1 or energy intakes were observed between HIIC and LICC, with or without stratifying for gender. Significant differences in post exercise non-esterified fatty acid (NEFA) concentrations were observed between intensities in both genders, coupled to a significantly lower respiratory exchange ratio (RER) following HIIC (P=0.0028), with a trend towards greater reductions in RER in men(P=0.079). In conclusion, high intensity exercise, if energy matched, does not lead to greater appetite or energy intake but may exert additional beneficial metabolic effects that may be more pronounced in males.

Now widely adopted on courses throughout the world, the prestigious Nutrition Society Textbook series provides students with the scientific basics in nutrition in the context of a systems and disease approach rather than on a nutrient by nutrient basis. In addition books provide a means to enable teachers and students to explore the core principles of nutrition and to apply these throughout their training to foster critical thinking at all times. This NS Textbook on Sport and Exercise Nutrition has been written to cover the latest information on the science and practice of sport and exercise nutrition. A key concept behind this textbook is that it aims to combine the viewpoints of world leading nutrition experts from both academia/research and a practical stand point. Plus where necessary there are additional practitioner based authors to ensure theory is translated into practice for each chapter in the form of either 'practice tips' or 'information sheets' at the end of relevant chapters. The textbook in essence can be divided into three distinct but integrated parts: Part 1: covers the key components of the science that supports the practice of sport and exercise nutrition including comprehensive reviews on: nutrients both in general and as exercise fuels; exercise physiology; hydration, micronutrients; and supplements. Part 2: moves into focusing on specific nutrition strategies to support different types of training including: resistance; power/sprint; middle distance/speed endurance; endurance; technical/skill, team; and specific competition nutrition needs. The unique format of this textbook is that it breaks down nutrition support into training specific as opposed to the traditional sport specific support. This reflects the majority of current sport and exercise requirements of the need to undertake concurrent training and therefore facilitating targeted nutrition support to the different training components through the various macro and micro training cycles. Part 3: explores some of the practical issues encountered in working in the sport and exercise nutrition field and includes key sport related topics such as: disability sport; weight management; eating disorders; bone and gut health; immunity; injury; travel; and special populations and situations. READERSHIP: Students of nutrition and dietetics at both undergraduate and postgraduate level. All those working in the field of nutrition and related health sciences. © 2011 The Nutrition Society.