Can Carbohydrate Restriction in conjunction with Exercise Enhance Metabolic Flexibility and Improve Markers of Health, in Males and Females?

Project ID: SST_SHAPE_8

Intermittent fasting (IF) is a novel weight loss method, whereby calorie intake is restricted to a daily 4-8 h eating window. This avoids some of the pitfalls associated with traditional dieting, such as calorie counting, and can achieve additional health benefits compared to conventional dieting (e.g., improved insulin sensitivity). Benefits of IF can be enhanced by exercising during the fasting period, with one study showing that training before breakfast improved insulin sensitivity more than exercising after breakfast.

Our recent research has found that eating early in the day and fasting in the evening is the optimal version of IF, due to interactions between nutrient intake and circadian physiology. But evening fasting corresponds with when hunger typically peaks and may disrupt social occasions centred on an evening meal. Our recent work also found that IF can cause ‘undesired weight loss’, reducing lean mass more than traditional dieting.

Benefits of IF may be driven by increased metabolic flexibility, which is an increased ability to metabolise fat. Both fasting and carbohydrate restriction blunt insulin release, causing a metabolic shift towards fat oxidation, which suggest the metabolic effects of fasting can be replicated by restricting carbohydrate exclusively. The negative effects of IF on body composition, hunger, and social activities, could also be mitigated by restricting carbohydrate and permitting intake of protein and fat. As with fasted exercise, coupling exercise with carbohydrate restriction may enhance benefits, by up-regulating metabolism to meet the energy demands of exercise, thereby enhancing mechanistic adaptation pathways in muscle and adipose tissue. However, this has not been previously investigated.

This PhD will explore the use of periodised carbohydrate restriction to enhance metabolic health, with the objective of developing a combined nutrition and exercise strategy that can support weight loss and benefit long-term health. The project will combine whole-body metabolic and behavioural measures with adipose and muscle cell tissue gene expression analysis, providing insight into both the mechanistic and ecological effects.

The PhD will address the following aims:

Aim 1: Establish if evening carbohydrate restriction can influence whole-body metabolism and improve insulin sensitivity.

Aim 2: Investigate the behavioural effects of evening carbohydrate restriction with exercise on appetite, physical activity, and sleep.

Aim 3: Using biopsy methods, determine mechanistic effects of evening carbohydrate restriction with exercise on muscle and adipose tissue gene expression.

Aim 4: Assess the feasibility and acceptability of evening carbohydrate restriction with exercise to promote beneficial effects on metabolic health.

Supervisory Team:

DOS: Dr David Clayton (ECR)

• Dr Clayton is an expert in nutrition and exercise metabolism and successfully supervised his only internally funded PhD student to completion in November last year. This work will generate five publications and has helped expand collaboration networks, with a portion of that project taking place at University of Bath. Dr Clayton has published over 30 papers and attracted over £155,000 of external research income from charity and commercial sources.

Co-Supervisor: Dr Emma Sweeney (ECR)

• Dr Sweeney specialises in the role of exercise and nutrition to enhance sleep quality. Dr Sweeney will contribute to study design, data collection and the measurement/analysis of sleep. Dr Sweeney has attracted over £50,000 funding from charity sources.

Co-Supervisor: Prof. Mark Christian (NTU Biosciences Department)

• Prof. Christian’s research is examining the mechanisms that regulate gene expression in adipose tissue. This is an interdisciplinary project that will provide an opportunity to expand Prof. Christian’s research into interventional human models. Prof. Christians expertise in gene expression analysis being crucial to the mechanistic work of the project. Prof. Christian has attracted over £800,000 funding from the BBSRC.

Co-Supervisor: Prof. James Betts (University of Bath)

• Prof. Betts is a world-leading expert in nutritional physiology. Prof. Betts has substantial experience in conducting ambitious, interdisciplinary PhD projects, combining metabolic, behavioural, and cellular mechanistic aspects in humans, such as the proposal herein. Prof. Betts will guide and support the completion of this project, providing opportunities for training and networking with University of Bath, which will facilitate larger cross-institutional grant applications on similar topics and outcomes. Prof. Betts has attracted over £2 million funding from UKRI, charity, consultancy, and industry sources.

For the eligibility criteria, visit our studentship application page .

This is part of NTU's 2024 fully-funded PhD Studentship Scheme.