JCAB limit for BMI is 30, I will post from the manual:
The applicant must not be obese to the extent that such obesity may interfere with the
performance of airman duties.
2. Disqualifying Conditions
Excessive obesity that may interfere with the performance of airman duties
3. Examination Procedures and Precautions
4. Evaluation Precautions
Obesity is one of the significant risk factors for arteriosclerosis and cardiovascular
disease. An applicant with severe obesity with body mass index (BMI) exceeding 30
must be examined for other risk factors of cardiovascular disease and evaluated for
qualification with consideration given to the risk of sudden incapacitation during
flight. Also, evaluation should be made to determine whether or not the condition
interferes with the controlling of the aircraft.
BMI is calculated according to the formula given below.
BMI = body weight (kg) / height (m)2