I'm a 25 year old male currently weighing 235 lbs (~106 kg) and I am 5'9 (~175 cm). For the majority of my life has been sedentary, I have never consistently exercised for any significant period of time.
I have been cycling for around 1-2 hours a day 4-5 times a week in the evening consistently at 13 m/h (20 km/h) with medium resistance.
I have been taking in 700-900 calories daily. I take multivitamins in the morning, eat one 110 calorie Jack Link's jerky snack pack for lunch and one 400 calorie Soylent drink for dinner. Throughout the day I drink 1-2 Diet Cokes. The rest of the calories are made up with an occasional snack in the morning which is usually a banana or doughnut.
So far I've lost 15 lbs (~7 kg) (down from 250 lbs) over the past two months down from, but I'm afraid that my diet might not be sustainable.
Is this an adequate plan purely for healthy weight loss? If not, what changes should be made?