• Login
• Admin

Ardavani, Arash (2024) Very low-energy diets in overweight-to-obese, middle-aged men with type two diabetes mellitus or prediabetes: the musculoskeletal and metabolic effects of adjunct high-intensity interval training. PhD thesis, University of Nottingham.

PDF (CORRECTED PhD Thesis (Unhighlighted Version).) (Thesis - as examined) - Repository staff only until 31 July 2025. Subsequently available to Anyone - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader Available under Licence Creative Commons Attribution. Download (8MB)

Abstract

Background

The worldwide progression of the obesity and diabetes mellitus dual epidemics has generated an increased interest in the feasibility of very-low energy diets (VLEDs) as a potential treatment for either disease state. However, concerns have been raised in relation to the potential of diet-induced sarcopenia in population subgroups which exhibit a default susceptibility to primary sarcopenia. Exercise has frequently been explored as a potential attenuator of lean body mass (LBM) reductions in hypocaloric states through altered rates of muscle protein synthesis (MPS) and breakdown (MPB). The musculoskeletal, cardio-metabolic and vascular effects of VLEDs, with or without HIIT, when applied to a sarcopenia-prone cohort of middle-aged male patients with either obesity or an overweight status, is investigated through the VLCDeXDM trial.

Methods

Human interventional trial with a randomised-controlled, supervised, open-label design, consisting of two arms (800kcal/day VLED-only versus an equivalent VLED intervention with HIIT), undertaken in a single-centre setting. Male patients with either insulin-independent type 2 diabetes mellitus (T2DM) or prediabetes, aged 30-to-65 years and a body mass index (BMI) of 27-to-50kg/m2 were recruited. An intervention duration of six weeks, with baseline, peri- and post-intervention assessments occurred. VLED meals were provided by LighterLife ®.

To address existing deficiencies within the literature, separate systematic reviews and meta-analyses investigating the impact of VLEDs with differing exercise modalities (aerobic exercise training (AET) and resistance training (RET) on body composition, and the outcomes of exercise modalities to multiple indicators of response, were also performed.

Results

VLED-Exercise Meta-Analysis: VLED+AET appears to result in enhanced weight loss when compared with VLED monotherapy. VLED+HIIT may resemble this effect: However, VLED+RET does not, although indirect evidence of LBM retention may exist.

Exercise Response Meta-Analysis A total of 62 data-points were procured. Both AET and HIIT training exhibited differential improvements in VO2peak based on intervention duration. VO2peak did not adequately differentiate between AET and HIIT, irrespective of intervention length. Although none of the other exercise response indicators achieved statistical significance, LT and HRrest demonstrated common trajectories in pooled and separate analyses between modalities. RET data was highly limited.

VLCDeXDM Trial: Participants in the VLED-HIIT group lost more total and fat mass (-11±3.64kg, p<0.001 & -6.39±1.86kg, p<0.001, respectively) versus VLED-Only (-8.76±2.41kg, p<0.001 & -6.15±2.16kg, p<0.001, respectively). However, estimation of MPS, as measured by fractional synthetic rate, revealed a greater reduction in VLED-HIIT (-0.95±0.52%·day−1, p=0.003) than VLED-Only (-0.54±0.29%·day−1, p=0.003). Further, LBM loss was found to be greater in VLED-HIIT (-3.54±1.27kg, p<0.001) than VLED-Only (-2.53±2.36kg, p=0.03). Paradoxically, although within-group MPB measures were non-significant, a larger proportion in the VLED-HIIT group exhibited a reduction post-intervention (60% versus 20%) and an improvement in muscular strength (38.6% participant-exercise response rate versus 25%). VLED-Only also preferentially improved glucose-related parameters. Evidence of other cardio-metabolic improvements in VLED-HIIT over VLED-Only were also demonstrated.

Conclusion:

VLED-Exercise Meta-Analysis: Substantial heterogeneity exists across the extant evidence-base. Limitations are identified, recommendations to facilitate further developments and personalisation of treatment is discussed.

Exercise Response Meta-Analysis: Heterogeneity was ubiquitous across all analyses. The potential for LT and HRrest as indicators of exercise response requires further elucidation, in addition to the exploration of interventional and intrinsic sources of heterogeneity.

VLCDeXDM Trial: VLEDs were safely implemented and well-tolerated in both groups. The presented, novel evidence concerning LBM retention is conflicting and requires further investigation. The potential mechanistic explanation for the observed paradox is established within this thesis. Additional scientific research in addition to these novel findings is recommended. The utility for VLED-HIIT in specific clinical scenarios is also explored.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Idris, Iskandar Phillips, Bethan Atherton, Philip
Keywords:	diet, exercise, very low energy diet, high intensity interval training, weight loss, muscle mass, skeletal, muscle protein synthesis, muscle protein breakdown, diabetes, metabolic syndrome, metabolism
Subjects:	W Medicine and related subjects (NLM Classification) > WD Disorders of systemic, metabolic or environmental origin W Medicine and related subjects (NLM Classification) > WK Endocrine system
Faculties/Schools:	UK Campuses > Faculty of Medicine and Health Sciences > School of Medicine
Item ID:	79582
Depositing User:	Ardavani, Arash
Date Deposited:	11 Dec 2024 04:40
Last Modified:	11 Dec 2024 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/79582

Actions (Archive Staff Only)

Edit View