How To Lose Body Fat?

I am 51 yrs, single by choice with a a history of lumber compression in the past,( 20 yrs back). Bending and exercises without supervision not recommended. I have simple bengali meals of rice, dal, fish curry at lunch, 2 roti with a veg sabji at night, 2 slice bread with omlette at breakfast most of the days. I walk 2kms 3 days a week usually. I sit for at least 1-2 hrs after meals. I am 10 kg overweight acc to my BMI calculation done recently. I don t look obese but I am not able to reduce my belly and lower chest fat. Can u suggest some less stanuous exercise and diet?