The big breakfast study: chrono-nutrition influence on energy expenditure and body weight

在过去三十年中，肥胖症的流行在世界范围内已达到流行病的程度，并被认为是一个主要的健康问题，因为它与心血管疾病、中风和某些癌症等非传染性疾病有关。管理超重和肥胖的方法可能集中在饮食和生活方式解决方案上，以达到减肥的负能量平衡，因为临床药物和手术方法针对病态肥胖。目前关于体重管理的饮食建议基本上是基于“卡路里就是卡路里”的假设，这些卡路里在一天中什么时候摄入并不重要。最近的证据挑战了这一假设，表明我们可能比晚上更有效地利用或消耗早晨消耗的卡路里，这是控制体重的有益策略。这意味着在实际生活中，你会在早餐时间摄入更多的卡路里，而在晚餐时摄入更少的卡路里。在英国，一天的正餐通常是在晚上，这很容易导致体重增加。这些研究表明，在一天中的所有时间，卡路里的代谢并不均匀，消化、吸收和利用的过程受到一天中的时间的影响。研究还没有严格调查一天中吃正餐的时间如何影响能量平衡。可能是早餐吃得多导致身体更活跃，或者确实，晚上吃得多导致不活动。或者，人体的自然生物节律对早晨摄入的卡路里反应更灵敏。进食后，能量消耗增加，这被称为“食物热效应”（TEF）。我们将探索增强早晨（早餐）TEF反应的机制和适应时间过程，作为一种消耗额外卡路里的手段，这是由人类自然昼夜节律变化（与光-暗周期有关）驱动的，这种变化可以在早晨最大化，以提高能量利用率。早餐后增强的TEF有助于增加24小时的能量消耗，如果食物摄入保持稳定，体重会随着时间的推移而下降。许多作者研究了24小时能量消耗，特别是在瘦-肥胖差异的背景下，但很少有人考虑昼夜节律，也没有人研究超重/肥胖受试者的胃排空的相互作用。我们的假设是，进食的时间会影响能量平衡和体重，因为与晚上相比，早上的能量消耗会被放大。早上能量消耗增加的原因尚不清楚，这是否与自然生物昼夜节律或行为适应有关。这一假设将通过两项受控饮食干预研究来解决，这两项研究将检查：(i)一天中主餐的时间（早餐和晚上）对减肥过程中代谢和行为调节的影响，以建立早晨进食时驱动能量消耗增加的生物机制；（ii）膳食消耗时间对能量平衡的影响是否通过正常的生物昼夜节律来调节。拟议的工作旨在表明，在英国，我们目前的膳食消耗模式，早餐少，晚餐多，违背了我们的内部生物钟，这加剧了成功控制体重的困难。从公共卫生的角度来看，这项时间营养研究提供了一个机会，为关于何时进食以促进减肥的转化研究提供了循证数据。这些研究可以潜在地支持早餐重要性的公共健康信息，并为促进体重控制提供了另一种策略。

During the past three decades, the prevalence of obesity has increased worldwide to epidemic proportions and is considered to be a major health problem because of its association with non-communicable diseases, such as cardiovascular disease, stroke and some cancers. Approaches to manage overweight and obesity are likely to be focused around diet and lifestyle solutions to achieve negative energy balance for weight loss, as clinical pharmaceutical and surgical approaches are targeted for morbid obesity. Current dietary advice for weight management is broadly based on the assumption that a 'calorie is a calorie' and it does not matter when these calories are consumed throughout the day. Recent evidence has challenged this assumption, suggesting that we may utilize or expend calories consumed in the morning more efficiently than in the evening, which is a beneficial strategy for weight control. This would mean in practical terms that you would consume more calories at breakfast time as the main meal of the day, and less during the evening meal. In the UK, the main meal of the day is most often in the evening, which pre-disposes to weight gain. These studies suggest that calories are not metabolized equally at all times during the day, and that the process of digestion, absorption and utilization are influenced by the time of day. Studies have not rigorously investigated how time of eating of the main meal of the day influences energy balance. It may be that eating a larger meal at breakfast time leads to being more physically active, or indeed, a larger meal at the evening leads to inactivity. Or, that the natural biological rhythms in the human body are more responsive to calorie ingestion in the morning. After eating, there is an increase in energy expenditure, this is termed, 'thermic effect of food' (TEF). We will explore the mechanisms and time-course of adaption for enhanced morning (breakfast) TEF response as a means to dissipate extra calories, driven by the natural circadian variation in the human (related to light-dark cycle), which can be maximized in the morning for increased energy utilization. An enhanced morning TEF after breakfast could contribute to increased 24-h energy expenditure and, if food intake remained stable, weight loss would thus ensue over time. Numerous authors have studied 24hr energy expenditure particularly in the context of lean-obese differences, but few have considered circadian rhythms and none have studied the interaction with gastric emptying in overweight/obese subjects.Our hypothesis is that timing of eating influences energy balance and body weight, because morning energy expenditure is amplified in comparison to evening. The cause of the increased energy expenditure in the morning is unclear, whether this is linked to natural biological circadian rhythm or behavioral adaption. This hypothesis will be addressed through conduct of two controlled dietary intervention studies that will examine, (i) the impact of the time of the main meal of the day (breakfast Vs evening) on metabolic and behavioral regulation during weight loss to establish the biological mechanisms that drive elevated energy expenditure when eating in the morning, in overweight men and women(ii) whether time of meal consumption effects on energy balance are modulated though the normal biological circadian rhythmThe proposed work aims to show that our current meal consumption pattern in the UK, of having a small breakfast and large evening meal is working against our internal biological clock and this exacerbates the difficulties in successful weight management. From a public health perspective, this chrono-nutrition study offers an opportunity to provide evidence-based data for translational studies on when to eat to promote weight loss. These studies can potentially support the public health message of the importance of a breakfast meal and offers an alternative strategy to promote body weight control.