When I was a teenager, I weighed 143 at my top. What a curse. But I gradually got it off by age 30 and have been 110-115 lb. ever since. Now I'm 63 y.o. and weigh 112. Here are some important things I've learned:
A healthy diet for weight management is a healthy disease-preventive diet as well. Being overweight is a risk factor for cancer and other diseases, as are alcohol and smoking.
The best diet is low in fats, sugars and salt, and high in raw plant foods. Olive oil, avocados and other "good fats" are OK but dairy should be minimal.
Organic foods are best for disease prevention. Agricultural chemicals we ingest through the food chain are a huge risk factor.
Do not eat processed foods. Period. They are filled with salt, chemicals and sugar.
Do not drink sodas. Even some fruit juices are loaded with sugar. Cut real juice with sparkling water for a healthy "soda."
Use lemons in salads and drinks. Eat grapefruit with a little maple syrup, honey or agave juice if the fruit is sour. Squeeze oranges and make your own OJ
Always have extra (undressed) salad or veg. sticks ready to go; also a light dressing (olive oil/vinegar or lemon base, add a little real maple syrup to sweeten).
Ripen fresh fruit a handful at a time daily on your windowsill. Some people don't like fresh fruit b/c it's not ripe. Also, food tastes better when it's not cold.
Have unsalted or just lightly salted nuts around for snacks.
Dress popcorn with vinegar, soy sauce and nutritional yeast.
The list goes on but these are just a few tips