All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions.
A fasting person abandons food, beverages and all kinds of fast nullifiers for the sake of Allah, as He The Most Exalted Prepared a great reward for him. In this regard, the Prophet (PBUH) said: "Allah said: The Fast is for Me and I will give the reward for it, as he (the one who observes the fast) leaves his sexual desire, food and drink for My Sake. Fasting is a screen (from Hell) and there are two pleasures for a fasting person, one at the time of breaking his fast, and the other at the time when he will meet his Lord. And the smell of the mouth of a fasting person is better in Allah's Sight than the smell of musk." [Related by Al-Bukhary].
Therefore, there is no harm on wishing to have food for a fasting person so long as he pertains his fast and didn't break it, even if this made him hesitates to change the intention of not fasting since this won't nullify his fast. In this regard, Al-Imam An-Nawawi (May Allah Have mercy on his soul) stated: "If a fasting person hesitates as regards breaking his fast due to a person manner towards him, wishing to have a meal and the like but only made his intention while observing fast. There are two opinions on this:
The first one: His fast is invalid.
The second one: His fast is valid, and this opinion is the most preponderant one and adopted by our doctrine (Sahfiee's school of thought) and the majority of Muslim scholars." [Al-Majmmoa' Sharih Al-Mohathab, vol. 3/pp.285].
Accordingly, at the time where the prophet (PBUH) had an offer to have everything (Great amount of gold that equal the size of a Mecca's valley) as he (PBUH) said: "My Lord presented to me, that He would make the valley of Mecca into gold for me, I said: "No O Lord! But being filled for a day and hungry for a day"-or he said: "three days" or something like that- "So when I am hungry, I would beseech You and remember You, and when I am full I would be grateful to You and praise You." [Related by At-Tirmithi].
Furthermore, commercial food ads that merchandize lawful food product is permissible whether in Ramadan or at any given time so long as they do not contain unlawful ingredients. We should follow the footsteps of Omar Ibn Al-Khattab (May Allah Be Pleased with him) as he said: "Abandon what hurts you." [Shoa'ab Al-Iman vol.12/pp.47]. The latter statement means: a person should be away from any matter which might harm a person whether in this life or in the Hereafter.
In conclusion, if visiting some websites might reduce fasting person effort to observe fasting due to the above ads, then it is reprehensible to visit similar websites in order to preserve one's fast valid. And Allah Knows Best.