Obesity is a major health hazard, with increased risk for cardiovascular disease (mainly heart disease and stroke), type 2 diabetes, musculoskeletal disorders (especially osteoarthritis) and certain types of cancer (endometrial, breast, and colon). The World Health Organization (WHO) estimated that in 2005, approximately 1.6 billion adults worldwide were overweight and at least 400 million were obese. Further, the WHO estimated that at least 20 million children under the age of 5 years were overweight. The projected numbers for 2015 are larger, with 2.3 billion adults expected to be overweight and 700 million expected to be obese.
The cause of excess body weight is an imbalance between energy intake and expenditure. The WHO has identified a global shift in diet towards increased intake of energy-dense foods that are high in fat and sugars but low in vitamins, minerals and other micronutrients. At the same time there is a trend towards decreased physical activity due to the increasingly sedentary nature of many forms of work, changing modes of transportation, and increasing urbanization.

In most diets, carbohydrates are the greatest source of calories. Carbohydrates are polyhydroxy aldehydes, ketones, alcohols and acids that range in size from single monomeric units (monosaccharides) to polymers (polysaccharides). Before being absorbed by the body, carbohydrates must be broken down into monosaccharides. This breakdown occurs due to two major enzymes: amylase and glucosidase.

The glycemic index (GI) is defined as the incremental area under the blood glucose curve following ingestion of a test food, expressed as a percentage of the corresponding area following an equivalent load of a reference carbohydrate, either glucose or white (wheat) bread . Factors that influence the GI besides the composition of the carbohydrate are the fat and protein content of the food, the acidity of the food and the presence of fiber. Low GI foods (< 55) include vegetables, unsweetened yogurt and protein-enriched spaghetti. High GI foods (> 70) include white bread, baked potato and dates.

Digestion of carbohydrates begins in the mouth, with amylase secreted by salivary glands. This action accounts for only about 5% of the breakdown of carbohydrates. The process is halted in the stomach due to the high acid environment destroying the amylase activity. When the food enters the intestine, the acidic pH is neutralized by the release of bicarbonate by the pancreas and by the mucous that lines the walls of the intestine. Amylase is secreted into the small intestines by the pancreas.
Alpha-amylase inhibitors with activity against mammalian forms of the enzyme are present in plants and it is suggested that they were developed by plants in order to strengthen their defense against predators. Plant constituents with enzymatic inhibitory activity include polyphenolic compounds and glycoproteins. For example, anthocyanins and ellagitannins present in raspberries and strawberries have been reported to inhibit alpha-glucosidase and alpha-amylase activity, respectively.
In addition, theaflavins and catechins present in green and black teas have been reported to inhibit alpha-amylase and alpha-glucosidase activity as well as retard starch digestion in an in-vitro model.
Alpha-amylase inhibitors are also present in grains, including wheat and rice. However, the greatest body of research has gone into glycoproteins extracted from kidney beans (Phaseolus vulgaris) and more specifically on the proprietary Phase 2 product.
The alpha amylase inhibitor prevents starch digestion by completely blocking access to the active site of the alpha-amylase enzyme.
The optimum pH for the inhibitor is 4.5 to 5.5 and the optimal temperature is 22 to 37°C. There is no activity at 0°C and the inhibitor is completely inactivated by boiling for 10 minutes.

Experiments conducted with the Phase 2 alpha-amylase inhibitor indicate that it reduces the rate of absorption of carbohydrates, thereby reducing the GI of foods. The evidence also indicates that Phase 2 promotes weight loss when taken concurrently with meals containing carbohydrates. The importance of reducing the GI of foods in weight management and type 2 diabetic control is indicated by an emerging body of evidence. Reducing the post-prandial spikes of glucose and insulin following a high GI meal may also reduce the risks of developing insulin resistance, which can lead to cardiovascular disease.

A randomized, double-blinded, placebo-controlled study was conducted on 60 pre-selected, slightly overweight volunteers, whose weight had been essentially stable for at least six months. The volunteers were divided into two groups, homogeneous for age, gender, and body weight. The test product containing Phaseolus vulgaris extract and the placebo were taken one tablet per day for 30 consecutive days before a main meal rich in carbohydrates.
The results of this investigation show that, when taken daily by overweight human subjects with the carbohydrate-rich portion of a 2000- to 2200-calorie diet, a dietary formula containing Phaseolus vulgaris extract as the major ingredient produced significant decreases in body fat while essentially maintaining lean body mass. Phaseolus vulgaris extract appears to be a safe and effective aid to consider in weight loss/maintenance programs.