Temperature fluctuations or feelings of being really sick without any visible problems with temperature readings is quite common, I used to feel like I had a severe case of the flu all the time. I'd check my temperature, but it would be normal. I know you're not eating right. Here are some comments based on your diet:
6:30am- soy protein shake made with nonfat milk
STAY AWAY FROM SOY. It contains high levels of phytic acid, which the human body has no way of processing. So what happens is your body attaches vitamins and nutrients INSIDE OF YOU to molecules of the acid so it can pass through your digestive system. This, in turn, wears you down even more. If you've ever seen a sickly looking vegetarian, this is why, they eat too much soy. Milk is essentially a simple sugar, a dissachride in fact. Some people have no trouble with it, but it is actually a pretty quick rise in blood sugar. It's safer to have unsweetened almond milk. And keeping out fat may actually be the problem, try whole milk first, organic if you can afford it.
9:30am- 1/2 of whole wheat english muffin with peanut butter
I bet that muffin is NOT whole wheat. Check the label. If it doesn't say 100% whole wheat, guess what, it ISN'T. You should only be eating sprouted grain products, and they do make english muffins like that. Peanut butter? Tsk, tsk. It should be avoided. I bet you didn't even check the label. If you're eating a brand like Peter Pan, and even a number of organic varieties, there's added sugar. Look if you don't believe me. If you have unsweetened though, it should still be avoided. Sunbutter is the best alternative. The organic type is the only kind you can get because the others have added sugar. Unsweetened almond butter is good too, but avoid cashew and peanut butters. They're actually beans, not nuts, so they affect blood sugar much differently.
12pm- 1/2 of whole wheat english muffin with peanut butter
See above.
1:30pm- 1/2 of lean roast beef sandwich with mustard on whole wheat roll & half bag of baked chips
Roast beef often has added sugar, I'm not kidding. Check. Check your mustard too. Read above about grain. STAY AWAY FROM POTATO CHIPS. You will not be able to eat them for awhile, maybe not ever again. They're very, very, very bad for you. You seriously might as well be eating straight sugar it's that bad. Baked makes no difference and is actually probably worse because of the lack of fat.
4:30pm- other half of sandwich and chips
Read above.
7pm- usually skinless chicken breast with small serving of either boiled red potatoes or brown rice (no butter or any other toppings)
Potatoes should probably be avoided at first, I avoid ALL root vegetables based on some old Chinese data I read about it. Wild rice is best if you want to try it. Butter actually is not good to avoid, it helps you. It should be organic, however, with added omega fats if you can afford it.
Read this:
http://ehealthforum.com/health/topic119108
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