I'm not singling out fructose, it's just one component of overall health and diet. Just like how a lot of people look at GI as the single holy-grail thing to monitor, I just wanted to point out that there are multiple inter-related factors; some of which may be contradictory. Yes, the most relevant and biggest contributor to the majority of health issues we face to day is simply volume, eating way, way too much for the level of activity that we do. Life isn't exactly life & death nowadays where you have to spend hours tracking down and foraging for food everyday, thus making you get some exercise for the meager calories that you get to consume each day. Now we've got an abundant number of choices in mega-calorie super-sized meals and a lot of people just sit behind a desk all day.

Monitoring GI, playing around with types of food and timing meals, juggling complex vs. simple carbs, fructose vs. sugar vs. artificial-sweeteners are just the tip of the iceberg as far as addressing the real problem, simply eating way, way too much.


It's not the actual sugar we have to worry about, it's the concentration. Simple carbs and table-sugar (sucrose) are digested fast and goes into your bloodstream quickly. This raises blood-glucoses and leptin levels which gives your brain the "I'm full, I'm happy" feeling and you can stop eating. That's why they also tell you to eat slowly, so that the food first entering your body has a chance to digest and get into your bloodstream. Otherwise, you'll continue to eat well beyond the volume that's necessary to raise your blood-sugar due to the time-delay of digestion. Proteins take longer to digest and raises insulin moderately.

Depending upon how high that blood-sugar gets, a certain amount of insulin is pumped in to regulate it. Insulin triggers your muscle-cells to absorb glucose from the bloodstream and convert to glycogen to replenish its energy stores. At the same time adipose fat-tissue is signaled to convert the glucose into fats and store it. Perfectly normal biology. The problem comes in with sedentary lifestyles where your muscle-cells aren't exercised and their glycogen stores (2000 calories total) are fully stocked up. Then all of the excess glucose and protein in the bloodstream goes into building up fat-storage. The problem here is not insulin or glucose, it's that you're eating food when you don't need it, and the excess is converted into fat.

What happens when you eat too much simple-carbs/sugars is it increases your blood-sugar by A LOT. Then the body dumps in A LOT of insulin to quickly make your cells absorb that glucose. However, like with eating quickly, there's an overraction and time-delay. The extra insulin ends up overcompensating and makes your cells suck up too much glucose from the bloodstream. This lowers your blood-sugar by too much and your brain, which burns primarily glucose, ends up not having enough energy and this is the cause of the laziness you feel after a big meal (also stomach hoards blood for digestion, further starving the brain of glucose).

As you can see, in sedentary people with fully stocked-up glycogen stores, excess glucose & protein mostly gets converted into fat. By eating more complex carbs, or in srrs's case, simple-carbs trapped within fibre of fruits & veggies, the digestion-rate and glucose-absorption into the bloodstream is slower. This triggers less of the insulin-response and a less immediate conversion to fat. The slower digestion and more steady blood-glucose gives you time to burn off that meal in activity over the next couple of hours as it digests rather than having it go straight to fat. That's the basis of GI.

However, when you're working out and exercising (and recovery afterwards), the goal is different, you want to get glucose into your cells as fast as possible to replenish the glycogen that's being consumed. In which case, you want low-GI simple carbs found in energy drinks & gels. These spend the least amount of time sitting around in your intestines and gets to the cells quickly. Due to the limited digestion-rate of 200-250 cal/hr, ingested carbs is always playing a losing catch-up game with the depleting glycogen stores, your blood-sugar level will always be declining during exercise if you're working out at a rate of more than 200-250 cal/hr.

There's some minor debate about eating too much too far ahead of time before a workout and triggering a dip in blood-sugar due to the insulin-spike. However, the results of studies have shown no impact on performance whatsoever. That's because your glycogen stores are fully-stocked and the low blood-sugar just indicates that the meal has been transfered from your bloodstream into your muscle-cells, right where you want it. It's just that your brain that feels sluggish from low blood-sugar, but your muscles are fully stocked and ready to go!

As for the final question, when you're exercising, blood-sugar and insulin drops, the analogue to insulin, glucagon is actually increased. This has the opposite effect as insulin, triggering your cells with high glycogen-stores (unused muscles) to dump its supply into the bloodstream and increasing blood-sugar levels. Also triggers your fat-cells to dump its fat-stores into the bloodstream to supply energy to the working muscles.