Translation:You will have to eat with less sugar starting today.
This answer is not correct. We would never say "eat with less sugar". It would be "eat less sugar" or "use less sugar". Also, in general, we need to be able to report when a given answer is not correct and that is not a choice now, so I am commenting here instead.
Looking at another fragment of the sentence, "have to eat with less" has only 8 google results. "have to eat less" 2,380,000 result. That "with" needs to go.
What happens if you change sugar with salt: You will have to eat with less salt starting today.? The meaning in spanish is that you have to put less sugar (salt) i your meals, it is not excatly no to eat sugar as a thing.
Other mistake in the translation is the use of 'starting', the meaning is quite the same, but if you use starting the sentence in Spanish should be 'Tú tendrás que comer con menos azúcar empezando hoy.'. I think the translation into English is 'You will have to eat with less sugar from today'
"From today" is unnatural in American English. Starting today is correct.
Okay I'm going to invent a term here. This is what I would call an "explicative translation". What you want is what I would call a "normative translation". Explicative translations are very helpful when you are reading the Spanish and saying, " okay what does this word mean? What is its function?" Normative translations would be saying this is an what American might typically say who was in a good mood this morning when he woke up and was on his best behavior.
I wrote "You will have to eat less sugar from now on (which, to me, sounds natural and expresses the idea of the sentence) and it was accepted by DL.
AY!!!!!!!!!!!!!!!!!!!!!! I'm pushing 60 and this language gets harder by the day to learn!!!!!
To me, a better answer in English would be, "You must eat with less sugar starting today." This answer was not accepted even though it expresses the same meaning with fewer words.