Oh my goodness! I had the same problem...until recently. I found out that I am insulin resistant, which is a more common problem than you may realize. I'm not a doctor, so I can't explain what goes on in the body, but basically, my body can't process sugars very well. In the past, no matter how much I exercised, or how much "good" food I ate, my belly just seemed to stay the same size or even got bigger. It was very depressing.
Then, about 3 months ago, I went to the Dr. in a fit of depression about my bulging waistline and weighing the most I've weighed EVER! I asked her to check my thyroid, so she ran a whole range of blood work on me. The blood work showed pretty clearly that I was insulin resistant. Metabolic syndrome and Syndrome X are other names for the condition. She made some suggestions for how to change my diet, and then I went home and shopped online for books and other resources to help me learn about my condition. Here is a list of books I suggest you read:
1) "Bring Your Triglycerides Down Naturally" by Andrew Mierzejewski (this one was an absolute WEALTH of information for more than just lowering triglycerides)
2) "You On A Diet" by Michael F. Roizen and Mehmet C. Oz (this one is good about going into what happens inside the body)
3) "The Sugar Solution" by the Editors of Prevention Magazine
4) "The Good Carb Cookbook"
5) "The Abs Diet" by David Zinczenko
These will be a good start, and then I also recommend you pick up a few more cookbooks such as "Sugar Busters! Quick and Easy Cookbook".
I would also recommend you check out
www.drnatura.com for information on total body cleansing. I just finished a round of antibiotics, so I decided this was a good time to start my 2nd cleanse on this product. Antibiotics are very bad on the body and promote the growth of candida, which creates a craving for sugar, which feeds the candida and breeds more candida, which crave more sugar...and for someone who is insulin resistant, this is a bad thing. My belly was starting to get that pooch the week my antibiotics ended, and I was craving sugary foods (both sweet and starchy) like none-other, so I knew the candida was a-multiplyin'! The cleansing product kills candida and helps stabilize the production of good bacteria in the body so that candida is kept in check. I've been on my cleanse for only 3 days, but I can already see and feel a difference in my midsection. The pooch is definitely going down and the sugar cravings are already subsiding.
With all that said, here are my observations about a few things you said in your post:
1)
You eat meal replacement shakes with peanut butter and banana. Meal replacement shakes are notorious for being packed with hidden sugars and artificial sweeteners, which are VERY bad for the body (how they got approved by the FDA is beyond me). The banana is loaded with sugar, too. If you are insulin resistant (and it sounds like you are), this is bad bad bad. Also, meal replacement shakes are not like real food, despite what anyone says. They are NOT real meal replacements. You'd be better off eating a stick of part-skim mozzarella cheese with a handful of raw almonds.
2)
You eat popcorn or hard boiled eggs as an afternoon snack. Popcorn is full of starch, which is just another way to say "sugar". Bad bad bad for insuline resistant folks except in moderation. The hard boiled egg, on the other hand, is great, especially if it's an organic egg that's not pumped full of antibiotics and steroids.
3)
You eat a lot of soy based foods. The soy based foods you buy at the supermarket aren't as good for you as you have been led to believe. Only whole fermented soy can be considered healthy: miso, tempeh, and natto. The unfermented soy that is commonly found in supermarket products is considered "bad soy". The first book in my book list above goes into more detail about this.
A few suggestions: If you are, in fact, insulin resistant, the only fruits you should eat are strawberries, blueberries, raspberries, and kiwis. That's it. Cut out such starchy veggies as potatoes (all potatoes), carrots, and corn. Pasta? Bye-bye! Lastly, go through the nutrition labels of the foods you eat. Note the serving size and the amount of sugar per serving. Divide the grams of sugar by 4 and that will give you the number of teaspoons of sugar in a serving. You should not eat more than 12 teaspoons of added sugar per day. Orange juice adds about 5 teaspoons of sugar in an 8 oz. cup, for example. I think you'll find that as soon as you implement these suggestion, you'll start seeing your belly flatten and your weight drop about a pound or two a week. I know I have. I lost 13 poounds in about six weeks, and I'm still going.
Good luck!