赞同沅老师的解答。我再补充几点关于health和wellness的区别。

一般来说，health 侧重有没有疾病，wellness侧重对身体的保养，主动采取健康的生活方式和养生之道。请看国外网站对这两个词差别的解释：

Wellness is an active lifestyle that incorporates several components that affect health (physical, mental and social wellbeing) on a holistic level.

Wellness is an individual pursuit—we have self-responsibility for our own choices, behaviors and lifestyles—but it is also significantly influenced by the physical, social and cultural environments in which we live.

Wellness is often confused with terms such as health, wellbeing and happiness. While there are common elements among them, wellness is distinguished by not referring to a static state of being (i.e., being happy, in good health, or a state of wellbeing). Rather, wellness is associated with an active process of being aware and making choices that lead toward an outcome of optimal holistic health and wellbeing.

有些国家,如牙买加的卫生健康部英语为：Ministry of Health & Wellness 美国纽约大学有一个Health & Wellness Center. 这种用法，说明这两个词不能完全替代。Health 强调治病，含可以打针输液，而wellness 指健康保养，包括采取主动改变生活方式，营养搭配，体育锻炼等方法。

因此，问题句中的a wellness book 主要指介绍如何保持健康的书，而不是强调在医学方面如何治疗。