Last week's column shared an Israeli study that found the glycemic index (GI), a way to measure how fast and to what degree a food eaten in isolation raises your blood sugar, is not universal.

The established GI score for a ripe banana, for example, is 62. In this study, however, subjects were just as likely to score, let's say, a 56 or a 67. Yet that deviation doesn't render the GI useless.That's because subjects who experienced a less-than-normal rise in blood sugar and recorded a 56 always recorded a 56. Subjects who experienced a higher-than-normal rise in blood sugar and recorded 67 always recorded a 67.The Israeli study is proof of what I've professed for years: that since no two individuals are perfect metabolic matches, there is no such thing as a one-size-fits-all diet, only that you need to constantly experiment to create a diet that works for you.And that you need to embrace failure.**********Five days ago, you couldn't get over your good fortune. You read about the heightened mental state known as "flow" and that same day you actually experienced it.The old copy of the UC Berkeley Wellness Letter in the dentist's office calls flow a "feeling of being totally focused, absorbed and in control" and "at one with your action." A rower who finds his flow, according to the article, feels as if the oar is not a long pole with a blade at the end but an extension of his arm.Time seems to slow. A sense of control builds confidence. The rowing may really be really hard, but there's an element of euphoria to it.Later, as you picked tomatoes out of your garden, you thought about how much you enjoy eating them in your fist with just a bit of garlic salt. Immediately you walked inside, washed one, and bit into it as if it were an apple.It was even better than you anticipated. You sprinkled some garlic salt where the tomato had been bitten, bit again, and totally lost yourself in the taste sensation.As you continued to eat, time seemed to slow. One thought dominated. That when they are in season and taste this good, you could eat tomatoes to start every meal and never get sick of them."That's it. That's it," you blurted out with clarity, confidence, and absolute joy. You had just experienced "flow." You were certain of it.You were also certain you now knew the best way to lose weight.Since the spring, you had been telling yourself you needed to diet, but after that Fitness Master guy wrote that the most successful ones were personalized and required trial and error, you couldn't muster up the motivation. But now you're champing at the bit to begin.Tomatoes are low cal, mostly water, so you decide to eat at least one, maybe two, as a way to fill up and eat fewer processed carbohydrates at lunch and dinner until the end of the local growing season in September.Some quick research certainly supported your plan. A medium tomato only contains 22 calories but 292 mg of potassium, 1.5 grams of dietary fiber, one-fifth of your daily need for vitamin A, and one-fourth of that amount of vitamin C.Better yet, an article you found on WebMD.com written by Elaine Magee, a nationally known dietician who has written more than two dozen books, claims that "eating lots of tomatoes, any way you can, is a great thing [because] this fruit that acts like a vegetable is loaded with health properties."So you started the diet that night, but in a day or two you knew something was horribly, horribly wrong. Your hunger remained in check after breakfast, but you got absolutely ravenous after the meals that began with tomatoes.Late last night, it finally became too much.You took a bite of chocolate cake, and then another, and didn't stop until you realized nearly half of it was gone.So much for the experience of flow, you thought as you wondered what went wrong.**********What you just read was a fictionalized scenario of what actually happened to one of the 800 subjects in the aforementioned Israeli study prior to the study. The middle-aged woman, who was obese and suffering from pre-diabetes, had been eating tomatoes liberally because they are considered "good for you" - especially according to the GI.Consider how the subject is handled at Livestrong.com in an article titled "Glycemic Index of Tomatoes" by Dakota Karratti."At less than 15, tomatoes are considered a low-GI food. . . . Because of this, the tomato would be an appropriate vegetable to include in a low-GI diet plan, which might be prescribed for someone who has diabetes or difficulty controlling his weight."Now I've written 20 articles for Livestrong.com over the years and know their editors check facts closely. What Karratti writes mainstream medicos would tell you.And for most of you, the advice would be right.But for those of you in the story above, it would be horribly, horribly wrong.