The rate of obesity worldwide has doubled in 73 countries since 1980. Today 30 percent of North Americans and 10 percent of the world's population are obese, an estimated 604 million obese adults and 108 million obese children. A recent article suggests that this world-wide increase in obesity is driven by the huge companies that make processed foods, sugared drinks and refined carbohydrates, and the extensive advertising they do for their products (NEJM, June 12, 2017). The authors say, "Increased availability, accessibility, and affordability of energy-dense foods, along with intense marketing of such foods, could explain excess energy intake and weight gain among different populations."

The worst culprits are foods that have had:
• sugars added to them, and/or
• fiber removed from them.
Investigative reporters from the New York Times showed that the western food giants such as CocaCola, Nestle, General Mills and Pepsico are aggressively marketing these cheap, calorie-dense, low-fiber foods to developing countries (NYT, Sept. 15, 2017).

How Fiber Helps to Control Weight
A key to controlling weight is to eat lots of foods that are full of fiber and avoid foods that have had their fiber removed (Adv Nutr, January 2013;4:16-28). There are two types of fiber: soluble and insoluble. Insoluble fiber is not absorbed and passes from your body. Soluble fiber is absorbed primarily in the colon, and many human epidemiological studies, clinical trials and animal studies show that fiber helps change the bacteria in your colon to lower blood sugars, reduce the inflammation that increases cancer risk, and lower body fat.

Almost all of the sugars added to foods are absorbed soon after they pass into the stomach. The natural sugars IN fruits, vegetables and other plant foods come with soluble fiber, a gel that binds to the sugar and prevents its absorption in the upper intestinal tract. When the sugar/soluble fiber combination reaches your colon, bacteria there break down and ferment the soluble fiber to release the sugar from the fiber. Far less sugar is absorbed in your colon than would have been absorbed in your upper intestinal tract.

How Added Sugars Lead to Obesity
When you eat foods with added sugars or drink any beverage that has sugar in it, you have little or no soluble fiber to delay the absorption of sugar into your bloodstream, so sugar is absorbed as soon as it enters your intestines to cause high rises in blood sugar levels. Your pancreas responds by releasing large amounts of insulin into your bloodstream and the excess sugar is converted into a type of fat called triglycerides. Then HDL cholesterol carries the triglycerides out of the bloodstream into your fat cells and your liver. When you have excess fat in your liver, your liver cannot accept sugar so blood sugar levels remain high, which can cause diabetes. When you continue to accumulate excess fat in your fat cells, you become obese.

Are Western Food Giants Changing Gut Bacteria World-Wide?
Your colon has several trillion bacteria in it, and it appears that certain bacteria in your colon may determine whether you are fat or skinny (JAMA Oncol, January 26, 2017).
• What you eat may be far more important than just how much you eat in determining which bacteria grow in your colon and therefore how fat you are (Int J Obes (Lond), Sept 8, 2017).
• Foods based on refined carbohydrates and other types of processed foods encourage the growth of certain bacteria in your colon that can make you fatter and more likely to become diabetic (Diabetes Care 2015 Jan; 38(1):159-165).

Most of the bacteria in your colon are classed as Bacteroides (good) or Firmicutes (bad). The good Bacteroides convert fiber to short chain fatty acids (butyrates) that reduce inflammation and insulin resistance and lower high cholesterol (Clin Chem, 2013;59(4):617-628). The bad Firmicutes make acetates associated with increased risk for obesity and diabetes (Nature, 2016;534(7606):213-217), and they also invade the cells lining your colon to cause inflammation and insulin resistance (Clin Ther, 2015;37(6):1172-1177).

Your Gut Bacteria Eat What You Eat
What you eat determines which types of bacteria grow in your colon because bacteria eat the same foods that you do. Eating a high-fiber, plant-based diet is a safe and effective way of changing colon bacteria to help control obesity and high blood sugars (Gut Microbes, Jan-Feb, 2012;3(1):29-34). Several studies show that vegans and vegetarians who eat a high-fiber diet have higher colon levels of the good Bacteroides (Eur J Clin Nutr, 2011;66(1):53–60), and as you would expect, obese people have more of the bad Firmicutes than good Bacteroides (Nature, 2006;444(7122):1027-1031). Switching from a low-fiber to a high-fiber diet began to change the bacterial content in human colons in just 24 hours (Science, 2011;334(6052):105–8).

In a new study, Danish researchers measured the colon bacteria in 62 overweight people and put them on either a high fiber or a low fiber diet for 26 weeks. Those who had high ratios of bad bacteria to good bacteria benefited most from the high fiber diet, probably because it reduced the levels of the bad bacteria that had made them fat, and thus helped them to lose weight (Int J Obes (Lond), Sept 8, 2017).

My Recommendations
A review of the world's literature from 1966 to 2008 showed that a Mediterranean diet is associated with long life and reduced obesity, diabetes, heart attacks, certain cancers, Parkinson's disease and Alzheimer's disease. The typical Mediterranean diet is based on high-fiber foods: fruits, vegetables, whole grains, beans, seeds, and nuts; with some fish but almost no red meat and limited dairy (Brit Med J, Sept 2008; NEJM, Feb 25, 2013).

If you want to prevent or reverse excess weight and diabetes, I believe that you should follow a Mediterranean-type diet pattern and eat lots of vegetables, fruit, whole grains, beans, nuts and other seeds. Avoid or restrict the foods that have no fiber (all foods from animals) or have had the fiber removed (such as fruit juices or foods made from flour). If you need to lose weight, I recommend following this diet pattern with a program of intermittent fasting