Hi Kunal!
I had gone through your query and understand your concern.
Losartan (Losar) is an oral medication that belongs to a class of drugs called
angiotensin receptor blockers (ARBs) and is used for treating
hypertension.
Side effects reported included diarrhea,
muscle cramps, dizziness, insomnia, and
nasal congestion. Losartan also may cause a persistent cough, increase serum potassium, impotence, and angioedema.
I don't think this symptoms you are having are due to Losartan side effects.
It can be a temporary situation,a condition that may last a few days without any medical significance.
If this lasts more than 1-2 weeks than you should see a doctor and he will perform you a physical examination and other tests.
In this case If I were your treating doctor I would think of
hypothyroidism and I would send you to do a thyroid test to confirm or exclude this diagnose.
I think of hypothyroidism because you are to young to have essential hypertension(I mean without an obvious cause ) and this weight gain with feeling weak and lazy are symptoms that this conditions cause.
But I suggest to see a doctor only if this symptoms continue more than 1-2 weeks.
Hope i was able to help you.
Take care.
Dr.Rovena