Wa Alaikum Assalam,
Your situation is different from someone who is simply feeling normal hunger. Islam does not expect you to harm yourself in order to prove strength. Fasting is an act of worship, but Allah has clearly allowed concession (rukhsah) for the sick. The Qur’an explicitly says that if someone is ill, they can fast later when they recover. This is not a weakness in faith — it is part of the law itself.
If you are feeling:
Severe weakness
Dizziness
Nausea
Risk of vomiting
Or signs that your health is worsening
Then breaking the fast is permissible.
There is a difference between: • Normal hunger and thirst (which are part of fasting) and Physical deterioration due to illness. If your weakness is coming from sickness, not just ordinary hunger, then you are already within the category of concession.
Your intention at suhoor was correct. Making intention to fast while knowing you may need to break it if your health worsens is completely valid. That is not sinful.
Your brother is correct in one sense — we cannot break a fast just because we feel “hungry.” But when illness is involved, the ruling changes. Islamic law is not blind to medical reality. If fasting:
Aggravates illness
Delays recovery
Causes real harm
Then breaking the fast is allowed, and sometimes even recommended. You are not expected to collapse before breaking it. Religion is not about pushing your body beyond safe limits. Allah does not gain anything from your suffering. The fast is for your spiritual growth, not physical damage. If your condition becomes genuinely difficult, you can break the fast and make it up later when you are healthy. There is no sin in using a concession that Allah Himself has given. If symptoms are strong or recurring, it would also be wise to consult a doctor.