The above mentioned hadith dissuades us from gluttony and lust of the eye [gaze].
Moderation in food [consumption] i.e. eating, is an issue that most of us are unfamiliar with and we do not know what important effect it has on health, from the body’s point of view hygiene and the spirit/soul.
We deduce that gluttony is of two aspects, namely physical and spiritual.
[A] The Physical Aspect
It has been established that a number of diseases and other health disorders are caused by over eating. Experts and physicians reason that microbes penetrate the body through four common agents namely; air, food, water and sometimes through the skin, and that there is not a distinctive method of hindering their entry.
If this very skin which serves as a block to the influence of microbes is bruised, it is very likely that microbes will easily find their way into the body through these particular openings and therefore, breaking the protective shields provided by the skin. For this reason we are always exposed to the danger of various kinds of microbe attacks and diseases. Naturally our body’s defensive system detects and ensures that all signs of infection in the body are checked and brought under control.
There is a claim that excess fat which accumulates between various folds of the body tissues serves as breeding ground for all sorts of microbes. It is true, for instance, if garbage or domestic rubbish is left in an area for a long period of time, it starts to break down or ferment and becomes a breeding ground for infections and diseases. In order to treat such infection [this pertains to infection in the body] it is really important to burn down these excess fats in the body and this can be achieved by fasting.
This analysis is of vital importance and it should be taken into consideration , since everyone will notice that when excess amount of food is present in the body and not absorbed or used , it piles up and eventually result in overworking and straining of the heart. In other words, a heavy task or load has an adverse effect on all organs of the body. So the heart and the rest of the body organs quickly get infected and diseased, this will in turn reduce one’s life span. Therefore if one desires to have sound health, he should improve his eating habits by taking only adequate amounts of food that the body requires and avoid over eating especially those people who do very little physical activities [or manual work].
One Physician said; “I have 20 years of experience of treating various illnesses and my entire experience could be summarized in two  words; moderation in eating and exercise-sport.
[B] The Spiritual Aspect
This hadith points out three essential aspects with regards to the spiritual and psychological effect of gluttony.
 Gluttony leads to hard-heartedness
 It makes a person lazy and relaxed in performing his spiritual duties and rituals.
Common sense indicates that if someone eats up the full, for example, he fails to rise up for his morning prayers and if at all he gets up, he looks as though he was drunk and intoxicated. But when he lacks night meal and is able to rise up at azan time or even long before it, he feels at easy and in the mood to study and pray.
 Gluttony diverts one’s attention from sermon whereas Fast makes one tender-hearted and it helps to increase one’s spirituality. But when the stomach is full, his intellectual faculties fail to function effectively and this causes one to fall short of the glory of God.
Perhaps you have noticed that during the holy month of Ramadan observers tend to be very determined and ready to appreciate a sermon or admonition as hunger adds purity and brings joy to the heart.
What is meant by gaze [nazar] in this tradition? First it refers to the act of looking at the opposite sex with sexual desire, lust and vise-versa. This brings about uncontrollable passion. But it is not strange or improbable that the word ‘Nazar’ could convey a great deal of meanings, that is to say any kind of look or gaze that will incite and agitate one’s passion e.g. whenever he sees the latest model car he says to himself; I wish I owned a car like that one.
This mere look or gaze coupled with desire and on top want and need induces negligence or ignorance of a person into a worldly and materialist person. Otherwise a look that is cast as a result of an object that serves as a lesson or warning or is mysterious or wonderful, or a look with the wish to help remedy the plight of the poor and the needy or to view a sick person/patient in order to give him or her treat treatment, in such cases there is no harm in it.
Source: http://en.rafed. net/islamic-articles-v15-1030/miscellaneous/456-gluttony-and-uncontrolled-sexual-lust