For those looking to manage their weight, skipping or reducing dinner intake is a common practice. But does this approach align with scientific evidence? A 2022 study from the University of Aberdeen challenges conventional wisdom, revealing that meal timing—not just calorie restriction—plays a crucial role in appetite control and weight management. The research suggests that while total daily calorie intake remains the primary driver of weight loss, consuming more calories earlier in the day may help curb hunger and reduce overall food consumption. This article delves into the study’s findings, exploring how meal distribution affects metabolism, appetite regulation, and long-term health outcomes.
For individuals aiming to control their weight, eating less or outright skipping dinner is a common strategy. However, the scientific validity of this approach has long been debated. Does meal timing truly influence weight loss, or is total calorie intake the sole determining factor? A 2022 study led by Professor Alexandra M. Johnstone from the University of Aberdeen’s Rowett Institute, published in Cell Metabolism, provides compelling insights into this question. When food intake is fixed throughout the day, weight loss and energy expenditure are similar when eating more in the morning or evening, but consuming more calories in the morning will better control appetite and may help lose weight.
doi: 10.1016/j.cmet.2022.08.001.
The study involved two 4-week randomized crossover experiments with 30 overweight or obese but otherwise healthy adults (BMI 27–42 kg/m²). Participants were divided into two groups: the Morning-Loaded (ML) diet group, where 45% of daily calories were consumed at breakfast, 35% at lunch, and 20% at dinner; and the Evening-Loaded (EL) diet group, where the distribution was reversed (20% at breakfast, 35% at lunch, and 45% at dinner). Macronutrient intake (protein, carbohydrates, and fat) was kept consistent between the groups.
Figure 1. Study design flow chart, baseline (B) and washout (W) diets as energy intake (EI) equally divided between breakfast, lunch, and dinner (33% EI for all meals). EI during B and W was 1.5× resting metabolic rate. EI during ML and EL weight loss diets was 1.0× resting metabolic rate
Contrary to popular belief, the study found no significant difference in weight loss between the two groups (ML: Δ-3.33 kg; EL: Δ-3.38 kg). Body composition changes, including fat and lean mass, were also similar, suggesting that the timing of calorie intake does not drastically alter weight loss outcomes when total daily calories are fixed.
Figure 2: ML and EL weight loss diets resulted in similar weight loss when EI was controlled
However, the research uncovered a critical distinction: participants on the ML diet reported significantly lower hunger levels and reduced desire to eat throughout the day. Using visual analog scales (VAS), researchers observed that the ML group experienced diminished appetite, lower anticipated food consumption, and increased satiety compared to the EL group.
Figure 3. ML weight loss diet significantly reduced hunger and appetite compared with EL weight loss diet. (A) Mean scores of hourly appetite assessments for 3 consecutive days after the end of ML and EL diets. (B) Temporal appetite scores based on hourly VAS assessments for 3 consecutive days at the end of ad libitum ML and EL diets. (C) Temporal appetite scores during the experimental period
As a result, the ML diet provided a stronger sense of satiety, potentially causing a reduction in calorie intake during lunch and dinner, which in turn could contribute to weight loss.
The underlying mechanism lies in the role of gut hormones, which are crucial for regulating appetite and the rate of gastric emptying (which slows down in the evening). After an ML breakfast, the levels of gastrointestinal hormones that enhance satiety (PYY, GIP, and GLP - 1) were significantly higher compared to an EL breakfast. The greater appetite suppression with the ML diet was, in part, due to the larger meal size and calorie load, which extended the duration of gastric emptying. Thus, consuming more in the morning helps to increase the amount of intestinal contents and the duration of emptying, reducing the likelihood of overeating later in the day.
Figure 4. Large breakfasts on the ML diet resulted in greater changes in appetite hormones and slower gastric emptying compared with small breakfasts on the EL diet
Furthermore, both the ML and EL weight - loss diets induced similar changes in glucose, insulin, and blood lipid levels, and there was no difference in energy expenditure between the two.
In addition to the quantity and quality of food, the timing of meals in the morning, afternoon, and evening is closely related to metabolic health. A previous study published in Nature Communication pointed out that consuming breakfast and dinner later in the day is associated with an increased overall risk of cardiovascular disease. Although eating at night does not necessarily lead to weight gain, it is still essential to ensure a reasonable intake at the appropriate dinner time. This not only benefits weight loss but also promotes overall physical health.
Conclusion
The Aberdeen study underscores that weight loss ultimately hinges on maintaining a calorie deficit, regardless of whether more calories are consumed earlier or later in the day. However, front-loading calories at breakfast may offer a strategic advantage by naturally reducing appetite and preventing overeating later on. For those struggling with hunger pangs or late-night cravings, adopting an ML-style diet could make calorie restriction more manageable without sacrificing nutritional balance.
That said, individual preferences and lifestyles play a significant role in dietary success.