Health and Social Care Institute, School of Health and Social Care, Teesside University, Constantine Building, Tees Valley, Middlesbrough, TS1 3BA, UK.
Sports Med. 2017 Sep;47(9):1683-1688. doi: 10.1007/s40279-017-0683-5.
Obese adults and children can be referred to lifestyle weight management services (LWMS) in which physical activity and/or dietary advice are delivered. Service providers quantify the 'weight' change between an initial measurement and follow-up measurement(s), which could be 12-24 months later. A control group is usually absent. The aim of this article is to scrutinise the various LWMS objectives for this weight change that are recommended by UK authorities. UK guidelines recommend that an adult LWMS should (A) reduce the sample mean body mass of all enrolled adults by at least 3% and/or (B) reduce the body mass of at least 30% of adults by at least 5%. We highlight the potential for objective B to be met even if no LWMS is implemented, especially over the recommended follow-up periods of 12-24 months. This is due to unavoidable random within-participant fluctuations in weight over such periods of time. A ≥1 kg reduction in mean body mass is also to be expected, even without any LWMS. Therefore, we suggest that objectives A and B are too liberal. Obesity status in children is indicated by the body mass index (BMI) z-score. Nevertheless, another UK recommendation is for an LWMS to "maintain" or "reduce" the BMI z-score of 80% of the enrolled children. Besides there being no stated thresholds for "maintain" and "reduce", it is inconceivable to deem an LWMS successful even if 80% of children do not alter their obesity status and even if the remaining 20% of children actually increase their obesity status. Here, we think the BMI z-score has been confused with the body mass z-score. In conclusion, measurable objectives of UK-based LWMS need to be clarified, and possibly altered, to account for typical amounts of random variability in individual weight measurements over the service time period.
肥胖的成年人和儿童可以被转介到生活方式体重管理服务（LWMS）中，在这些服务中提供体力活动和/或饮食建议。服务提供者会量化初始测量值和随访测量值（可能在 12-24 个月后）之间的“体重”变化。通常没有对照组。本文的目的是仔细审查英国当局推荐的各种 LWMS 体重变化目标。英国指南建议，成人 LWMS 应该（A）降低所有入组成年人的样本平均体重至少 3%，和/或（B）降低至少 30%的成年人的体重至少 5%。我们强调，即使没有实施 LWMS，尤其是在建议的 12-24 个月随访期内，目标 B 也有可能实现。这是由于在这么长时间内，体重不可避免地会随机出现个体内波动。即使没有任何 LWMS，平均体重也预计会减少≥1kg。因此，我们认为目标 A 和 B 过于宽松。儿童肥胖状态由体重指数（BMI）z 分数表示。然而，英国的另一项建议是，LWMS 要“维持”或“降低”入组儿童 80%的 BMI z 分数。除了“维持”和“降低”没有规定的阈值之外，即使 80%的儿童没有改变他们的肥胖状态，即使剩下的 20%的儿童实际上增加了他们的肥胖状态，也可以认为 LWMS 是成功的。在这里，我们认为 BMI z 分数与体重 z 分数混淆了。总之，需要澄清英国 LWMS 的可衡量目标，并可能进行修改，以考虑到个体体重测量在服务时间段内的典型随机变异性。
