Glycemic index (GI) is supposed to be a measure of how rapidly a food is turned into sugar in the blood. \u00a0But as I have been reading about GI this week, the story gets muddier and muddier. \u00a0Glycemic index as reported is not a good measure of the body\u2019s insulin response. \u00a0In fact, insulin response in some studies<\/a> was found to have no relationship whatever to GI! \u00a0Combinations of food turn out to be very important. \u00a0Fiber and fats can be helpful, and there is a new category I have learned about recently called \u201cresistant starch\u201d which slows the absorption of other foods that are digested along with it. \u00a0Can drinking water with food slow digestion? \u00a0(I last blogged about this subject 2 years ago<\/a>.)<\/p>\n The idea of \u201cnegative calorie\u201d foods is very appealing. \u00a0Are there things that you can eat that actually make you thinner? \u00a0Are there foods that decrease the insulin impact of a meal, or that lead to lower absorption of food that is eaten together at the same meal?<\/p>\n <\/p>\n Glycemic Index and Glycemic Load<\/b><\/p>\n Glycemic Index was conceived as a characteristic of food ingredients, something that could be reported on a label. \u00a0The way it is supposed to work is that low GI foods are better, especially for diabetics, but preserving insulin sensitivity is a concern for all of us as we age<\/a>. \u00a0Glycemic Load (GL) was supposed to be equal to the glycemic index times the portion size. \u00a0But instead, the insulin response to food has turned out to be just as complicated as it can be<\/p>\n Insulin is a signal to the body that \u201cwe have all the sugar we need, thank you. \u00a0Take your calories and turn them to fat.\u201d \u00a0Insulin causes fat storage. \u00a0Insulin is associated with weight gain. \u00a0Weight gain and insulin resistance, together and independently, contribute to mortality risk.<\/p>\n <\/p>\n Inscrutability of Tables of Glycemic Index and Load<\/b><\/p>\n I knew that Glycemic Index (GI) was designed to measure the surge in blood sugar that comes from eating a particular food. \u00a0It was my naive expectation that sugar would have the highest GI, then starches, then whole grains, then beans, then nuts. \u00a0I thought that greens and fish and meat would have very low GI. \u00a0But the GI reference table confounded my expectations on every score.<\/p>\n The glycemic load [GL] is calculated by multiplying the number of grams of carbohydrates in a given food by its glycemic index [GI] (which measures how quickly the food is converted into glucose and released into the bloodstream). The glycemic load is an accurate measure of how much insulin your body will have to produce to neutralize the carbohydrates in a given food. [LEF magazine<\/a>]<\/em><\/p><\/blockquote>\n Turns out that this very common-sensical statement is far from true. \u00a0The first thing I had to learn is that GI is not standardized by energy value of the food, but by grams of carbohydrate. \u00a0Say a peanut is being compared to a potato. \u00a0The potato is almost all carb, but the peanut is only \u2155 carb. \u00a0So when they compare the glycemic response head-on-head, they compare 50 grams of potato with 250 grams of peanuts. \u00a0Of course, this is going to make the peanut\u2019s GI look bad. \u00a0The GL is supposed to correct for this, multiplying by a \u201cstandard portion\u201d, but the whole idea of a \u201cstandard portion\u201d is dubious.<\/p>\n By this same definition, meats and salad oils have an undefined GI. \u00a0This is not because they produce no glycemic response, but because they contain no carbs, so the GI measurement protocol is undefined.<\/p>\n Here is a table<\/a> from Harvard Medical school, the top one that came up in a Google search. \u00a0In my experience, it is no more or less unfathomable than others. \u00a0For example:<\/p>\n Perhaps you can explain the higher GI of whole milk if you assume that cream is finding a pathway to be burned as fuel within two hours. \u00a0And the low score for Coca Cola might have to do with burning sugar in response to cafeine. \u00a0But there are too many questionable numbers in this table for me to have any faith in it.<\/p>\n How is GI measured?<\/strong><\/p>\n The GI value of a food is determined by feeding 10 or more healthy people a portion of the food containing 50 grams of digestible (available) carbohydrate and then measuring the effect on their blood glucose levels over the next two hours. For each person, the incremental area under their two-hour blood glucose response (glucose iAUC) for this food is then measured. On another occasion, the same 10 people consume an equal-carbohydrate portion of glucose sugar (the reference food) and their two-hour blood glucose response is also measured. A GI value for the test food is then calculated for each person by dividing their glucose iAUC for the test food by their glucose iAUC for the reference food. The final GI value for the test food is the average GI value for the 10 people. \u00a0(Jennie Brand-Miller at Sydney University<\/a>)<\/em><\/p><\/blockquote>\n The big problem is in the \u201cportion of food containing 50 grams of digestible carbohydrate\u201d, which can be a very large or a very small portion, depending on the food. \u00a0Two additional problems are that different people have very different responses, and also that the body\u2019s response to foods tested in isolation is not a good indication of how the body responds to food combinations typical of a meal. \u00a0In this study<\/a>, GI for different breakfasts was computed by adding up the GIs for individual foods; when the subjects\u2019 insulin response was measured it had no relationship at all to the computed GI\u2014a correlation of zero.<\/p>\n <\/p>\n Combining fiber with carbohydrates<\/b><\/p>\n Adding fiber to a meal can reduce the subsequent blood glucose and the insulin spike [ref<\/a>]. \u00a0Wheat bran has been used to slow the blood sugar uptake for diabetics [ref<\/a>]. \u00a0Green leafy vegetables have a similar benefit [ref<\/a>, ref<\/a>].<\/p>\n Resistant starch<\/a> is, by definition, starch that resists stomach enzymes, and is not quickly digested. \u00a0It passes through the large intestine, where it is fermented by bacteria that thrive on it. \u00a0RS may cause flattulence or indigestion. \u00a0Often the symptoms clear up after a few weeks. \u00a0Green bananas and raw potatoes are natural sources of RS. \u00a0You can also buy it as a flour and mix it into foods. \u00a0This study<\/a> claims that resistant starch slows starch absorption and damps the insulin spike better than fiber. \u00a0In this study<\/a>, RS lowered fasting glucose and improved blood lipid profiles. Glucomannan (konjac), pectin, and guar flour are all reported to have similar effects to RS.<\/p>\n Personally, I have a hunch that fiber (and possibly resistant starch) change the intestinal flora in a way that lowers total food absorption. \u00a0You extract fewer calories from the same food. \u00a0However, this is almost impossible to measure directly, and to my knowledge the study has not been done. \u00a0Less controversially, adding fiber or RS to the diet affect your appetite and how full you feel, and affect the insulin response, which influences whether your body burns the calories or adds to fat stores. \u00a0In all events, I think it’s worth the experiment to see if you can lose weight by adding fiber to your meals.<\/p>\n In this context, it is no surprise that long-term studies show that diets rich in green leafy vegetables [ref<\/a>, ref<\/a>, ref<\/a>] and high in fiber [ref<\/a>,ref<\/a>, ref<\/a>, ref<\/a>] lower the risk of chronic disease.<\/p>\n <\/p>\n Water<\/b><\/p>\n Drinking water with food, or eating foods with high water content, dilutes the food in your stomach. \u00a0I find it reasonable that this alone should slow digestion, delay the absorption of sugar, lowering the effective glycemic load. \u00a0Is this a substantial benefit, or is it negligible? \u00a0I have been unable to find any data on this question. \u00a0There is good evidence that peope tend to eat less calories if they drink more water, especially right before a meal [ref<\/a>], so water can be a psychological aid to weight loss. \u00a0Eating foods with high water content also increases satiety, so that (most people) tend to eat smaller meals, and don\u2019t make up the difference later [ref<\/a>]. \u00a0Soups are a weight-loss strategy.<\/p>\n <\/p>\n Supplements and drugs that can damp your insulin response:<\/b><\/p>\n <\/p>\n Is Fructose worse than Sugar?<\/b><\/p>\n All sugars contribute to insulin resistance and accelerate aging. \u00a0Are some sugars worse than others?<\/p>\n Table sugar is sucrose, a 12-Carbon sugar. \u00a0It is made of two 6-Carbon sugars, a “dimer” of fructose and glucose. \u00a0High-fructose corn syrup (HFCS) has more fructose than glucose (55-65%) and honey is similar. \u00a0Agave is yet higher in fructose.<\/p>\n The name \u201cfructose\u201d would suggest that it is the sugar of fruits, but fruits in general don\u2019t tend to have more fructose than glucose. \u00a0Apple sugar is about 75% fructose, and melons are 65-70% fructose, but grapes, peaches, and berries are 50%, and bananas actually have less fructose than glucose. [from FoodIntolerance.org<\/a>]<\/p>\n Whether fructose or HFCS is worse than sugar has become a controversial question. \u00a0Life Extension magazine<\/a> and Mercola.com<\/a> are down on fructose, while Examine.com<\/a> and other health advice sources<\/a> tend to minimize the difference.<\/p>\n Both glucose and fructose go directly into the bloodstream, but glucose is the body\u2019s primary fuel, so the insulin response is determined by the glucose. \u00a0In terms of insulin spike, fructose is a lot better <\/i><\/b>than glucose. \u00a0Fructose has a much lower GI than glucose.<\/p>\n Despite this, there are two lines of argument against fructose<\/p>\n The best reference I\u2019ve been able to find on the subject is Basciano et al, 2005<\/a>.<\/p>\n Everyone agrees that it\u2019s best to minimize both glucose and fructose. \u00a0If you prefer to sweeten with glucose instead of fructose, it\u2019s sold as dextrose<\/a>, not as cheap as cane sugar, but cheaper than honey or agave or maple syrup.<\/p>\n <\/p>\n A Calorie is a Calorie is a Calorie – Not!<\/b><\/p>\n \u201cThe amount you weigh is exactly the difference between the calories you ingest and the calories that you burn exercising.\u201d \u00a0We hear this all too often. \u00a0Writers who should know better promote it as the \u201cFirst Law of Thermodynamics.<\/a>\u201d \u00a0This is dangerous nonsense.<\/p>\n In fact, the calorie content of a food is measured simply by burning it and collecting the heat that is released. \u00a0But the body’s efficiency in use of foods is a very complex affair, dependent on everything from how well you chew your food to which bacteria reside in your intestine. \u00a0Peanuts do not deliver the body as many calories as peanut butter. There are (lucky?) people with very inefficient metabolisms and (unlucky?) people whose bodies are able to extract every last calorie from any meal. \u00a0The bacteria that live in our guts digest food for us, but extract a toll in energy that they need for themselves. \u00a0Depending on the particular bacteria you have in your intestine, the toll may be only 10% of the food energy coming in, or close to half.<\/p>\n Roughage slows calorie absorption and helps to move food quickly through the intestine, with less total absorption. \u00a0Eat as much raw wheat bran as you can stomach, and think of it as a negative-calorie food. \u00a0A vegetarian raw foods diet is not for everyone, but if you can live with it, it is a sure way to lose weight. \u00a0Raw foods are poorly absorbed, and from our perspective, that\u2019s a good thing.<\/p>\n <\/p>\n The Bottom Line<\/b><\/p>\n Weight gain or lost is probably a good proxy for how well you are controlling your glycemic load.<\/p>\n Remember that weight is relative to your genetic body type. \u00a0A person who has a genetic disposition to being overweight is not at higher risk for diseases of old age unless he actually eats too much. \u00a0Conversely, people who are blessed with a \u201cthin metabolism\u201d can be unhealthy if they overeat, even if they don\u2019t look fat. \u00a0If you tend to being overweight and have to diet and work out constantly to keep your weight just above \u201cnormal\u201d, you are in the optimal position for health and longevity. [Read more<\/a>]<\/p>\n I suggest that you use your instincts and your experience to lower your glycemic response<\/a> to food, and not to waste time with the mysteries in the tables of glycemic index. \u00a0First cut out sugar, then work on reducing starch. \u00a0Refined carbohydrates are worse than whole grains, but in my own diet I\u2019ve eliminated all bread, pasta, rice, grains, and potatoes—so I can attest it\u2019s possible. \u00a0Beans and nuts are good protein sources if, like me, you don\u2019t eat meat. \u00a0My vegetarian version of the no-starch diet leads to moderate ketosis, less extreme than in a meat-based diet.<\/p>\n Combine fiber into every meal. \u00a0Eat large salads and other green vegetables. \u00a0Add raw wheat bran and\/or resistant starch to your foods.<\/p>\n Everyone should be supplementing with magnesium. \u00a0Consider chromium and metformin as well.<\/p>\n Eat soups. \u00a0Drink water before and during meals.<\/p>\n Fasting is a powerful way to preserve insulin sensitivity. \u00a0Concentrating all your daily eating in an 8-hour window counts as a short, daily fast [read more<\/a>]. \u00a0Longer fasts of one to four days have major benefits [read more<\/a>].<\/p>\n Exercise is the best general tonic for general health. \u00a0Exercise before meals<\/a> in particular is a great habit to culture. \u00a0Even a minute or two of vigorous exercise that gets you panting makes a big difference in your glycemic response to a meal.<\/p>\n","protected":false},"excerpt":{"rendered":"
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