Energy Intake

This study will investigate whether acute sleep deprivation affects appetite, eating behavior, and physical activity in both regular exercisers and physically inactive individuals.

Excess energy, obesity and obesity-related diseases are important global health issues. Although it is known that obesity is an issue of energy balance, the components of energy expenditure seem to be inter-related in complex non-additive ways. The aim of this study is to explore the downstream impacts of exercise on short term changes in both expenditure and energy intake. The primary question the investigators are asking is whether moderate to high intensity exercise influences the basal energy expenditure and/or energy intake/macronutrient preference in young adult males? (A similar study will be performed on females in a different registration). The investigators will use a specially designed feeding table to measure energy intake and macronutrient intake, which is easy to quantify intake compensation. Basal metabolism will be measured by hood indirect calorimetry. The investigators will explore the factors that influence the level of compensation in expenditure and intake, in particular body composition. Participants will be asked to come to the lab after 10 hours fast for body composition tests including Dual Energy X-ray Absorptiometry(DXA), Magnetic Resonance Image(MRI) and Bioelectrical Impedance Analysis(BIA). They will then be asked (not) to do 30 minutes of moderate-to-vigorous exercise after an energy-limiting breakfast, during which metabolic rate levels and changes in dietary composition will be recorded by gas exchange and standardized buffet. In addition, participants' subjective hunger and preferences will also be recorded by questionnaires. Venous blood will be collected to measure metabolic and hormone factors, blood glucose will be measured by Continuous Blood Glucose Monitor (CGM).

The purpose of this project is to investigate the effects of exercise at different times of day on 72-hour eating behaviour, physical activity and sedentary behaviour in physically inactive adults.

The goal of this clinical trial is to investigate the effects of acute passive continuous hypoxemia (simulated high-altitude at rest) on appetite and energy intake in healthy young female adults. The main questions it aims to answer are: * Does six hours of simulated high-altitude (5000 meters) reduce scores of subjective appetite and energy intake? * Do changes in appetite and energy intake persist in the hours following the end of hypoxic exposure? Researchers will compare the effects of simulated high-altitude to a control normoxia (sea-level) condition to see if exposure to low oxygen levels independently affect appetite and energy intake. Participants will: * Visit the laboratory for a preliminary screening session to assess eligibility. * Undergo two randomized, single-blind, experimental sessions consisting of six hours of passive exposure to normoxia or hypoxia in a climate-controlled chamber. * Consume foods provided from a curated list, served in ad libitum quantities, after leaving the laboratory to assess post-exposure energy intake.

Background: Measuring what people eat is a challenge in nutrition research. Traditional methods, like food diaries, rely on self-reporting of individuals, and suffer from poor accuracy and recall bias. Aims: This project aims to identify physiological biomarkers related to food and energy intake, which may be used to develop an objective tool to estimate individuals' food intake in future. Eating behaviours are accompanied by significant physiological changes such as skin temperature, blood oxygen saturation, pulse rate etc. The investigators intend to investigate whether monitoring these physiological changes can help us estimate eating behaviour, such as meal size, eating speed, and duration of meals. Study design: Ten healthy adults will be invited for two study visits at NIHR Imperial Clinical Research Facility. Each visit will last for approximately 2 hr. They will consume a high- and low-calorie meal designed by nutritional researchers in a randomised order. During eating events, the investigators will track their physiological changes via a bedside monitor and wearable sensors. Blood samples will be taken from participants to measure their glycaemic response. Associations between energy load, glycaemic response, and physiological changes will be investigated. Our findings may promote an accelerated development of a wearable tool for dietary assessment in future.

The purpose of this randomised control trial is to determine whether consuming PulseOn enriched crackers for breakfast influences post-prandial glycaemic response and markers of appetite (hunger, fullness, desire to eat) over 4 hours, and energy intake at an ad libitum lunch meal on the same day. Healthy individuals with no underlying metabolic disease will be recruited to take part in this study.