Re: Smaller portions will not work.
Glucose is the primary energy source for mammalian cells. Blood glucose is tightly regulated and the hormone insulin signals fat cells to immediately remove the glucose from the blood. If you are not diabetic (or prediabetic), glucose should not give you any problems (although the microbes in your gut might like it - strangely not E.coli...).
Sucrose is one molecule of glucose bound to a fructose molecule. Fructose must be metabolised by the liver and deposited as fat. All (well, most) of the more complex carbohydrates (polymers of many other sugars) need enzymatic (or microbial) degradation in order for the energy producing cells (our mitochondria) to be able to extract energy.
Diabetes is the inability to modulate blood glucose. This occurs in 2 major ways. Loss of insulin expression due to autoimmune damage (Type I). Insulin resistance due to the repurposing of cells to handle other metabolites (Type II).
With HFCS the ratio of glucose/fructose (40/60) forces the liver to become fructose efficient and less "glucose precursor for complex carbs", and therefore insulin no longer has the same effect as the liver captures all of the "sugar" as fat. (remember glucose needs no intermediate metabolism, it can be used in almost every cell in our body).
If you want to get a "biochemical" sense of what this all means, look at the nutrition of an apple versus any processed food of the same volume- the higher density using pure compounds versus the cellular substrate of the apple. Squeeze an orange and see how much juice you get!
The modern crisis with obesity is directly due to the bias in the media reporting the problem. HFCS is pushed by a corn lobby here and it is used as a cheap sweetener. The FDA publishes recommended calorie intakes which are massively out of date( and possibly a conflict of interest?). If you are overweight, you can get your metabolism directly measured, and that number is your personal target.
If you exercise below the aerobic limit, your body will preferentially start to burn fat (e.g walking). If you exercise above the aerobic limit, your body has to burn glycogen (how glucose is stored).
For every 1lb of fat extra, that is 3500 kCals of energy. Energy required to run 26.2 miles (a marathon) , approx 3500 kCals. But if you walk for 4 hours , you might burn 2000 kCals. Pretty amazing? Well humans have evolved to be efficient runners and not walkers - that is we get running for proportianately less than the effort to start walking.
if you are overweight and you are *able* to exercise, then diet and exercise works every time -that's physics.
if you are overweight and *unable* to exercise, then diet control is primary, however *any* exercise is better than none.
There is a lot we do not yet understand about human physiology. But in this case, the attempts to confuse the issue with "who is to blame". We all are. If you don't buy crap food, they won't sell it. But that also means you don't give it to your kids.
Industry may be guilty of selling toxic crap, but we are the ones buying it. It is up to *US* to find the correct diet/exercise regime for *OUR* bodies.