Allah condemned the disbeliever because they eat like cattle i.e. eating too much,
1. From Quran.
Allah says:
Certainly Allah will admit those who believe and do righteous good deeds, into Gardens under which rivers flow (Paradise); while those who disbelieve enjoy their life and eat as cattle eat; but the Fire will be their abode. [Surah Muhammad verse 12]
2. From Ahadith.
a) Imran bin Husain narrated that the Messenger of Allah(Peace be upon him) said: “The best of people are my generation, then those who follow them. Then, after them a people will come who increase in fatness, loving fatness, giving testimony before they are asked for it.” [Jami` at-Tirmidhi 2221, Sahih al-Bukhari 3650]
b) Narrated Abu Huraira: Allah’s Messenger (ﷺ) said, “On the Day of Resurrection, a huge fat man will come who will not weigh, the weight of the wing of a mosquito in Allah’s Sight.” and then the Prophet (ﷺ) added, ‘We shall not give them any weight on the Day of Resurrection ‘ (18.105)
[Bukhari Book 65, Hadith 4729]
3. Scholars understood that obese (Going overweight by eating too much) is forbidden.
an-Nawawi commented:
“فيه ذم السِّمَن”
In it there is condemnation of obesity. [Sharah Sahih Muslim (17/129)]
al Qurtubi said:
وفي هذا الحديث من الفقه ذمُّ السِّمن لمن تكلّفه، لما في ذلك من تكلف المطاعم والاشتغال بها عن المكارم، بل يدل على تحريم الأكل الزائد على قدر الكفاية المبتغى به التَّرفه والسِّمن. وقد قال صلى الله عليه وسلم: ” إن أبغض الرجال إلى الله تعالى الحبر السَّمين ” ومن حديث عِمران بن حُصَين عن النبي صلى الله عليه وسلم قال: ” خيركم قرني ثم الذين يلونهم ـ قال عِمران فلا أدري أذكر بعد قرنه قرنين أو ثلاثة
ـ ثم إن من بعدكم قوماً يَشهدون ولا يُستشهدون ويخونون ولا يُؤتمنون ويَنذرون ولا يوفون ويظهر فيهم السِّمن ”
وهذا ذمٌّ. وسبب ذلك أن السِّمن المكتسب إنما هو من كثرة الأكل والشَّرَه، والدعة والراحة والأمن والاسترسال مع النفس على شهواتها، فهو عبد نفسه لا عبد ربه، ومن كان هذا حاله وقع لا محالة في الحرام، وكل لحم تولد عن سحت فالنار أولى به؛ وقد ذمّ الله تعالى الكفار بكثرة الأكل فقال:
{ وَٱلَّذِينَ كَفَرُواْ يَتَمَتَّعُونَ وَيَأْكُلُونَ كَمَا تَأْكُلُ ٱلأَنْعَامُ وَٱلنَّارُ مَثْوًى لَّهُمْ }
[محمد: 12] فإذا كان المؤمن يتشبه بهم، ويتنعم بتنعمهم في كل أحواله وأزمانه، فأين حقيقة الإيمان، والقيام بوظائف الإسلام؟ٰ ومن كثر أكله وشربه كثر نهمه وحرصه، وزاد بالليل كسله ونومه، فكان نهارَه هائماً، وليله نائماً.
The fiqh of this hadith is that it has a condemnation of obesity which is due to “takalluf… Rather it is an evidence that it is prohibited to eat which is more than necessary due to which “Tarfah” and “Obesity is required. (i.e. eating too much so that one become fat is not allowed.)…
Narrated `Imran bin Husain:
“Allah’s Messenger (ﷺ) said, ‘The best of my followers are those living in my generation (i.e. my contemporaries). and then those who will follow the latter” `Imran added, “I do not remember whether he mentioned two or three generations after his generation, then the Prophet (ﷺ) added, ‘There will come after you, people who will bear witness without being asked to do so, and will be treacherous and untrustworthy, and they will vow and never fulfill their vows, and FATNESS will appear among them.”
This is condemnation the reason is that obesity is due to eating a lot… and leaving the nafs on shahwaat. So he is worshipping his nafs not his Rabb.. Allah condemned the kuffar due to overeating.
Allah says: “While those who disbelieve enjoy their life and eat as cattle eat; but the Fire will be their abode” [Surah Muhammad verse 12] [Tafsir al Qurtubi under Surah al Kahf verse 110]
4. This is about eating too much and getting fat, not about eating until one is full. Islamweb states:
Iyaadh said: [The following words from a hadeeth]:
“’They ate until they were full’ is evidence of the permissibility of eating until one is full. What was reported from the Prophet sallallaahu `alayhi wa sallam ( may Allaah exalt his mention ) and the Salaf (righteous predecessors) about the dislike of eating until one is full applies to doing this all the time, as this hardens the heart, makes one forget about the needy and their suffering, and makes him held accountable for more things. What is permitted is to eat one’s fill as long as he does not exceed the limits and it does not prevent him from fulfilling his obligations and does not constrict his breathing and cause indigestion. Whatever exceeds this extent is not permissible. The Prophet sallallaahu `alayhi wa sallam ( may Allaah exalt his mention ) said, ‘…but if he must (fill his stomach), then one third for food, one third for frink, and one third for his breath.’” [Islamweb]