Is this an adequate diet/exercise plan for weight loss?

Question

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?

Answer 1

Cycling is fine for exercise (if you’re not worried about building muscle), but your diet is far from being a long term solution.

Given your statistics, you should be burning roughly 3200 calories a day. Even without any activity whatsoever (lying in bed all day), you should be burning 2000 calories just to function properly. To lose weight long term, you need to keep your caloric deficit reasonable. If you starve yourself like you are currently doing, you’ll only hold yourself back and wreck your metabolism in the process. To lose weight, you should be eating 2500-2700 calories a day with your current level of activity and size. To slow down muscle loss, you’ll also want to make sure that you’re getting enough protein in your diet, try to get 0.5-0.8 grams per pound of your body weight (117-188 grams).

As you lose more and more weight, your body will need fewer and fewer calories. You’ll want to re-adjust your total to compensate for this. Google “TDEE Calculator” (Total Daily Energy Expenditure) and you’ll find several calculators that will calculate this number for you.