1.) You will underperform in work and life in general. You will be constantly tired, appear lazy to employer (practically speaking be lazy) and will make slower stupider decisions. You may end up weighting less, but will have hard time to keep up at work.

2.) Your body will adapt and become much more efficient in extracting calories from food - people who lost weight through fasting tend to gain weight very quick. Most of them can not keep the weight long term. That practically means you gain weight first time there is longer stressful period in work or life - when all your focus goes to project you are working on o family care or whatever.

3.) You do not eat just for calories - you need also various proteins, vitamins and what not. You are damaging your body by not giving it what it needs more then by being slightly overweight.

Yes, people who don't eat at all loose weight, but there is price to pay on their health and performance. It is true that western people tend to eat way more calories then necessary, but "just eat small portions till you have target weight" advice does not work long term.