Remember that just because the gospel (or word of God) is true, it doesnt mean that the people are always true to it. You will always find people in every religion that do not practice what they preach. We are ALL error. 
If you want to know the truth of ALL things, including what our savior, Jesus Christ and God our heavenly father really teach and have planned for us, dont learn it by the example of others,PLEASE!!!, 
Just pick up a book of GODS words and teachings,(free! from any mormon church, mormon missionaries, or mormon friend you have), and read these teachings for yourself. You can read more about the dietary commandments and teachings that members of The Church of Jesus Christ of Latter Day Saints(mormons)believe,from a book called: The Doctrine and Covenants,Section 89,(known as The word of wisdom) and the Book of Mormon. It actually discusses meat consumption (meat to be eaten sparingly)and many other guidelines for a healthy body, mind and soul.  
YOU ARE RIGHT! we DO need to choose wisely with everything we put into our bodies! We cant just avoid coffee and tobacco and be healthy. There is much more to it than that. 
You will see that if you pick these books up and read them for yourself. 
Many mormons are not true to their own scripture unfortunately, KNOW THIS!  
but I guess thats why God tells us not to put our trust in the arm of flesh(each other) but to put our trust in HIM, and HIS teachings.  
You can gain your own understanding and knowledge of the truthfullness of these teachings(testimony)if you PRAY, and ASK GOD to reveal to you of the truthfullness of these teachings,(Gospel of Jesus Christ or Book of mormon)- which is just another testament of Jesus Christ and if they are really true. HE WILL TELL YOU! He will tell you by how you feel (known as the holy ghost) and you will recognize it by a feeling in the deepest depths of your soul. It is a wonderful sensation to experience! 
I wish you all the best in your journey for truth. YOU WILL FIND IT IF YOU HAVE FAITH IN THE THINGS I HAVE SAID. I promise YOU this, and anyone else reading this, that these I have said are true.  
I have been a member of The Church of Jesus Christ of Latter Day Saints (the restored church of Jesus Christ) for over 8 years now, and my life has only improved in EVERY way. I have gained so much joy and happiness because of these truths, and the understanding and peace they bring.  
I KNOW that if you ask of God, doubting nothing, keeping your heart open to my message,that He will confirm to you the truth of these and all things. Your spirit will recognize truth when it hears it, trust in this. A sensation will come over you (the Holy Ghost), this is Gods spirit confirming to your spirit of the truthfullness of what you read, or hear. We all have this ability to recognize truth when we hear it. We just have to learn to trust in it and recognize it.  
Best of luck and may God bless you with the wisdom you seek! 
Sincerely, 
Amanda:) 
PS: another excellent website where you can access a ton of LEGITIMATE information and free copies of the these amazing scriptures is: www.lds.org