Obesity increases the risk of type 2 diabetes, cardiovascular disease, and certain cancers, primarily due to elevated abdominal fat storage. With nearly two-thirds of the UK population living with overweight or obesity, there is an urgent necessity for evidence-based public health guidance to promote healthy weight. Calorie deficit can facilitate weight loss and body fat reduction, leading to health benefits, such as improved blood glucose control. Current weight management advice centres on lifestyle modification, incorporating changes to diet and physical activity to support a calorie deficit. However, existing dieting recommendations fail to consider gender or age. This is a surprising oversight, as it is well established that health outcomes vary significantly between men and women across the lifespan. Further, the menopause may have an impact on fat storage linked to changes in sex hormones. Our recent research, involving both mice and humans, has indicated that females are less responsive to weight loss and fat reduction during dieting. This study aims to understand endocrine and metabolic sex-based differences in obesity and calorie restriction, with a particular focus on women's health. We plan to conduct a diet study with 75 participants, encompassing both younger and older men and women, to monitor changes in energy expenditure and body composition using gold-standard techniques, such as doubly-labelled water. Blood and abdominal fat tissue samples will be collected to investigate how sex hormones might elucidate these differences. The aim of the study is to enhance our understanding of diet and women's health to combat obesity and promote healthy ageing.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
75
3d maintenance diet (MT, fixed macronutrient composition of 15% protein, 30% fat and 55% CHO), fed to energy requirements (1.3 X RMR)
6 week calorie restricted high protein diet (CR, fixed macronutrient composition as 30% protein, 35% fat and 35% CHO) fed to energy requirements \[0.8 X Resting Metabolic Rate (RMR)\], with stepwise reduction of 100kcal/d at week 3 and 5
Rowett Institute, University of Aberdeen
Aberdeen, United Kingdom
RECRUITINGChange in body mass expressed as weight in kilograms (kg)
Measured using digital scale
Time frame: From baseline (day 1) to end of intervention (day 53); additional measurements taken three times a week throughout the intervention duration
Change in energy expenditure expressed in kilocalories per day (kcal/day)
Measured using stable isotope method - doubly labelled water (DLW) - with urine sample collection
Time frame: From day 11 (start of the calorie-restricted diet) to the end of the intervention (day 52); with additional doses consumed on day 25 and 39
Change in resting metabolic rate (RMR) expressed in kcal/day
Measured using ventilated hood indirect calorimetry
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53)
Change in bone mineral content in grams (g)
Measured using Dual Energy X-Ray Absorptiometry (DXA) scan
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53)
Change in total body water (TBW) in litres (l)
Measured using deuterium dilution, with urine sample collection
Time frame: From day 11 (start of the calorie-restricted diet) to end of the intervention (day 53)
Change in total body density expressed in litres (l)
Measured using BodPod air displacement plethysmography
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53)
Change in body fat-mass percentage (%)
Derived from Lohman's 4-compartment model (body mass; body density; total body water; and bone mineral content)
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53)
Change in non-esterified fatty acids (NEFA) concentration in fasted blood sample
Analysed by KONE
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53); also measured at midpoint of calorie-restricted diet (day 32)
Change in concentration of caloric-restriction (CR) related hormones in fasted blood sample
Includes: leptin, adiponectin, cortisol; analysed by ELISA
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53); also measured at midpoint of calorie restricted diet (day 32)
Change in sex hormones concentration in fasted blood sample
Includes: oestrogens, progesterone, androgens; analysed by high -sensitivity liquid chromatography-mass spectrometry (LC-MS)
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53); also measured at midpoint of calorie restricted diet (day 32)
Body height measured in meters (m)
Measured using stadiometer
Time frame: Only at baseline
Change in Body Mass Index (BMI) expressed as kg/m^2
BMI will be calculated using weight and height measures
Time frame: From baseline (day 1) to end of intervention (day 53); additional measurements taken three times a week throughout the intervention duration
Change in adipose tissue metabolism assessed by adipocite size
Measured via abdominal subcutaneous fat biopsy using fine needle aspiration and histomorphometry method
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53)
Change in adipose tissue metabolism assessed by phosphorylation of hormone-sensitive lipase (HSL)
Measured via abdominal subcutaneous fat biopsy using fine needle aspiration and immunoblotting method.
Time frame: From day 8 (start of the maintenance diet) to end of the intervention (day 53)
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