National Institute for Health and Care Research Applied Research Collaboration Wessex, University of Southampton, Southampton, UK.
Faculty of Health Sciences, University of Bristol, Bristol, UK.
Lancet. 2023 Nov;402 Suppl 1:S99. doi: 10.1016/S0140-6736(23)02142-6.
Later-eating rhythm (LER) refers to a later timing, greater energy intake, and higher meal frequency in the evening. The role of childhood LER in obesity development is emerging, but most evidence is cross-sectional. Cross-context comparison allows the improvement of causal inference in observational studies by comparing cohorts with different confounding structures. This method is applied to assess the causal effects of LER on adiposity, by exploring the likelihood of residual confounding due to socioeconomic status.
In this cross-cohort analysis, we used ongoing birth cohort data from the UK Avon Longitudinal Study of Parents and Children (ALSPAC) established in 1991, and the nationally representative China Health and Nutrition Survey (CHNS) collected in 1989-2011. Children with available data at age 7 years were eligible. We applied indices of inequality for assessing confounding structure by regressing LER/adiposity on the standardised score of socioeconomic status (SES) in each cohort. We used multivariable linear and binary logistic regressions to model cross-sectional and prospective associations between LER at 7 years of age and body-mass index (BMI) at ages 7 and 9 years in both cohorts. Analyses were adjusted by age, sex, ethnicity, residency, and socioeconomic status. We used a p value for the Cochrane Q-test obtained from meta-analysis to test for heterogeneity between cohorts.
We analysed data from 4019 children (2170 [54·0%] female; 1849 [46.0%] male) in ALSPAC and 1749 (788 [45·1%] female; 961 [54.9%] male) in CHNS. The associations between SES and LER or adiposity differed between ALSPAC and CHNS (SES and energy intake for evening main meal: b=1·81 [95% CI 0·81 to 2·81] vs -3·02 [-4·76 to -1·27]; SES and frequency of evening snacks: odds ratio [OR]=0·51 [95% CI 0·41-0·63] vs 5·71 [3·54-9·22]; SES and BMI: b=-0·42 [-0·65 to -0·18] vs 1·29 [0·75 to 1·84]). Positive associations between frequency of evening snacks and BMI were seen in both cross-sectional and longitudinal analyses in both cohorts (mean change of BMI with 1 day increase of consuming evening snacks b=0·09 [0·02 to 0·15]; 0·13 [0·03 to 0·22] kg/m per day in ALSPAC, and b=0·11 [-0·07 to 0·28]; 0·30 [0·07 to 0·52] kg/m per day in CHNS). No associations were found for energy intake. p values for heterogeneity ranged from 0·107 to 0·932.
Both cohorts showed consistent results despite varied dietary cultures and SES patterning of LER or adiposity. Energy intake in the evening or night was not associated with adiposity, whereas evening snacking was. More recent, high-quality cohorts are warranted to enhance the strength of the conclusions.
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晚进食节律（LER）是指晚上进食时间较晚、能量摄入较多、进食频率较高的一种饮食习惯。儿童时期的 LER 与肥胖发展之间的关系正在逐渐显现，但大多数证据都是横断面研究。跨情境比较可以通过比较具有不同混杂结构的队列来提高观察性研究中的因果推断能力。本研究采用这种方法，通过探索由于社会经济地位造成的剩余混杂的可能性，来评估 LER 对肥胖的因果效应。
在这项跨队列分析中，我们使用了英国阿冯纵向研究父母和儿童（ALSPAC）中正在进行的出生队列数据，该研究于 1991 年建立，以及全国代表性的中国健康与营养调查（CHNS），该调查于 1989-2011 年收集。符合条件的儿童为在 7 岁时具有可用数据的儿童。我们通过将 LER/肥胖与每个队列中社会经济地位（SES）的标准化评分进行回归，应用不平等指数来评估混杂结构。我们使用多变量线性和二项逻辑回归模型，在两个队列中，在 7 岁时进行 LER 与 7 岁和 9 岁时 BMI 的横断面和前瞻性关联分析。分析通过年龄、性别、种族、居住地点和社会经济地位进行调整。我们使用来自荟萃分析的 Cochrane Q 检验的 p 值来检验队列之间的异质性。
我们分析了来自 ALSPAC 的 4019 名儿童（2170 名[54.0%]女性；1849 名[46.0%]男性）和 CHNS 的 1749 名儿童（788 名[45.1%]女性；961 名[54.9%]男性）的数据。ALSPAC 和 CHNS 之间 SES 和 LER 或肥胖之间的关联存在差异（SES 和晚上主餐的能量摄入：b=1.81 [95%CI 0.81-2.81] vs -3.02 [-4.76-1.27]；SES 和晚上零食的频率：比值比[OR]=0.51 [95%CI 0.41-0.63] vs 5.71 [3.54-9.22]；SES 和 BMI：b=-0.42 [-0.65-0.18] vs 1.29 [0.75-1.84]）。在两个队列的横断面和纵向分析中，晚上零食的频率与 BMI 呈正相关（每天增加一次晚上零食消费，BMI 平均变化 b=0.09 [0.02-0.15]；0.13 [0.03-0.22]kg/m；在 ALSPAC 中，b=0.11 [-0.07-0.28]；0.30 [0.07-0.52]kg/m 在 CHNS）。能量摄入与肥胖没有关联。异质性的 p 值范围为 0.107 至 0.932。
尽管饮食文化和 LER 或肥胖的 SES 模式存在差异，但两个队列都显示出了一致的结果。晚上的能量摄入与肥胖无关，而晚上吃零食与肥胖有关。需要有更近期的高质量队列来加强结论的可信度。
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