I can see a point to the nutrition tag: if this site is meant to cover the Nutrition proposal, then dietitians and nutritionists will want to filter the non-nutrition question (and those uninterested in nutrition can add it to their ignored tags). Exercise and fitness, however, seem a bit too vague for me.
Yes, I think they are ineffective, redundant tags.
There are two types of tags which are explicitly discouraged: redundant tags and meta-tags.
Redundant tags are those that are already implied by the site topic. There's simply no value to tags like [exercise], [fitness], [health], etc. Even the [nutrition] tag has limited value. Efforts to coarsely sub-divide the site like that will fail. Tags are not meant (nor well-suited) for the task of dividing the entire site into large swaths for the purpose of participating in (or ignoring) a broad subject site-wide.
Meta-tags are a problem because they do not tell you what the question is about. They describe something like:
- The author's motivation for asking the question (stupid, funny, quackery, etc)
- What kind of question is being asked (subjective, poll, request, etc)
Each tag should be able to stand on its own to tell you what the question is about. For example: the tag "subjective", taken alone, doesn't tell you anything about what the question is about. If it cannot pass that acid test, remove it.