Is there any specific physical fitness or medical standard required for UPSC services?

Yes, UPSC has specific medical and physical fitness standards, though they vary significantly depending on the service you are allocated. All candidates must undergo a mandatory medical examination after the Personality Test (Interview) to ensure they are fit for duty. 

General Health Standards
All candidates must be in good mental and physical health. This means you should be free from any medical condition that could interfere with your duties. Common issues like high blood pressure (above 140/90), diabetes with complications, or heart issues are closely checked. Minor issues like a hernia or varicose veins might make you "temporarily unfit" until you have surgery to fix them.
Height and Chest Requirements
For most administrative roles like the IAS or IRS, there is no minimum height. However, for "Technical Services" like the IPS (Police), RPF, or Forest Service, there are strict minimums:

Men: Generally at least 165 cm for Police (163 cm for Forest).
Women: Generally at least 150 cm.
Chest: Uniformed services also require a minimum chest measurement with at least 5 cm of expansion.

Vision and Eyesight
While you can wear glasses for most roles, the standards are stricter for uniformed services:

Myopia (Nearsightedness): Total power allowed is usually limited to -4.00D for IPS, whereas it's more flexible for IAS (up to -8.00D).
Colour Blindness: This is a major factor. If you have high-grade color blindness, you will be disqualified from technical services like the IPS or Railways, but you can still join the IAS or IFS.

Physical Conditions
For the Police and Forest services, doctors will specifically check for flat feet, knock knees, or a squint. Having these conditions usually disqualifies you from those specific uniformed roles, though you remain eligible for the administrative ones.