The government touts a diet high in carbohydrates, while many weight loss experts and low carb advocates swear by low carbohydrate diets. So, what exactly are carbohydrates?
The scientific definition of carbohydrates is that they are biomolecules. Biomolecules are simply molecules produced by living organisms such as plants.
The main function of carbohydrates, or plant based foods, is to transport energy to our cells in the form of starch (the scientific term for starch is glycogen.) When we eat carbohydrates, our bodies produce the hormone insulin. Insulin tells the carbohydrates we eat whether to go to our muscle cells to be used as fuel when we move, or whether to be stored as fat. If our muscles have enough carbs, or glycogen, already then the carbs we eat are stored in our fat cells. If we eat more carbohydrates than our muscles need, the excess is converted to body fat.
There are two types of foods rich in dietary starches. Foods that your mother and grandmother commonly called "starches" and knew were "fattening" are foods high in carbohydrates, low in fiber, and energy dense. Energy dense means they deliver a lot of calories in a small amount of food, versus carbohydrate based foods that deliver very little calories per serving. An example is a cup of lettuce has about 20 calories versus a cup of plain white potatoes that has 170 calories.
The energy dense carbohydrates in foods like white rice, white pasta, white breads, and sugary fruits, fruit juices, and sodas are examples of carbohydrate foods high in calories. Most commercially produced carbohydrate rich foods like breads, baked goods, cakes, cookies, donuts, snack foods like crackers and chips, even those "diet" 100 calorie snack packs, are all high in refined carbohydrates. This means if you don't burn them of through activity right away, they will be stored as body fat.
Refined calories have been processed to removed most of their fiber. Fiber is the part of plant based foods that make them filling and generally low in calories like vegetables and most fruits. Removing the fiber makes carbohydrate based foods less filling, and higher in calories than when they're in their natural state.
The second type of dietary carbohydrates you'll find in grocery stores are unrefined carbohydrates like those found in unprocessed, whole vegetables, beans, legumes, and lower sugar fruits. These carbohydrate foods are rich in fiber. They're more filling and generally lower in calories than refined carbohydrates. This means you can eat more of them without getting a lot of calories. These carbohydrate foods are less likely to be stored as body fat. But research shows carbohydrates, particularly starches, should not be the bulk of your diet as the US government advises.
Next: What are the benefits of a low carbohydrate diet?
FATLOSS 101: How carbs, sugar and grains fatten you up!
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Nutrition 101: What are the benefits of a low carbohydrate diet?
Most people view low carbohydrate diets as weight loss diet. Actually low carb diets promote health as well. Does this mean eating now carbohydrates including fruits and vegetables? No. But following the government's dietary guidelines of a diet of primarily carbohydrates is not healthy, nor is it based on solid science.
The US government's recommendation to eat a diet rich in carbohydrates is based on a 1970s panel on nutrition chaired by then Senator George McGovern. McGovern was a fan of the Pritikin diet and believed vegetarianism was healthy. His aid who wrote up the guidelines was a vegan with no nutrition degree. Although nearly all of the nutrition scientists who testified before this panel disagreed with McGovern's strict dietary guidelines, McGovern prevailed. See video below. We were told as a nation to eat less meat and animal fat, and to eat more carbohydrates. This included eating plenty of government subsidized crops like corn, wheat, beet, and cane sugars. Unfortunately, most Americans eat too many processed, high calorie carbohydrates, and not enough unrefined low calorie carbohydrates.
These two things have driven the current obesity epidemic.
Science has since prevailed on the side of a low carbohydrate diet as a healthier option over the government's recommendation of approximately 300 grams of carbohydrates a day depending on body size and caloric needs. This type of low carb diet is hard to achieve on unrefined carbs like whole fruits and vegetables. To achieve the government's recommendations for carbohydrates, you'd have to eat a generous and fattening amount of low density, refined carbohydrates.
While whole fruits and vegetables deliver vitamins, antioxidants, and fiber. To manage body weight, limiting refined, processed carbohydrates that are high in calories is key. Most healthy, moderately active adults find they need between 20 to 100 grams of carbohydrates a day (depending on body size) to lose weight. Active people seeking to maintain weight need roughly 75 to 150 grams of carbohydrates per day. (Endurance athletes need more.) Simply put, the average Joe and Jane should swap the white potatoes for sweet potatoes, switch from bread to broccoli, and replace the donuts with oatmeal and berries. And don't be afraid to eat a healthy portion of meat, eggs, nuts, cheese, or other proteins and fats with your unrefined carbs.
The McGovern Report: The official government policy of promoting a lowfat diet had nothing to do with science and everything to do with politics.
For more info: The soft science of dietary fat: low fat diets don't help you live longer by Gary Taube. from "Science" Volume 291.
Health: The Myth of the Low-fat Diet ; For Years, We've Been Advised to Eat a Low-fat Diet in Order to Help Prevent Heart Attacks And Promote Weight Loss. But, Says Jerome Burne, the Latest Research Suggests That Such a Diet May Actually Do More Harm Than Good
The Association of Misleading Studies
Dr. Michael Eades, M.D. on studies showing low carbohydrate diets superior to low fat, and the resistance of the low fat diet advocates to admit the truth is out, Ancel Keyes' Lipid Hypothesis was a lie.
