There is a lot of buzz online, in the dog world, and even in the veterinary profession about the effectiveness of the "green bean diet." The logic of the diet actually has some sound science behind it. Unfortunately, when used with regular dog food it may result in nutritional inadequacies.
The Diet
In its simplest form, owners supplement 10 percent of the volume of their pets’ regular canned or dry meal with canned green beans. The green bean content of the meal is increased in 10 percent increments every 2-3 days until all meals consist of 50 percent regular food and 50 percent green beans. This final mixture is fed until the pet’s target weight is reached. The pet is then slowly weaned from the beans and back to all regular food.
The Science
Studies in humans, cats and dogs have all substantiated positive weight loss results when adding fiber to calorie restricted programs. Canned green beans provide extra fiber, are generally a hit with dogs, and only contain about 50 calories per can. Human subjects report a greater sense of satiation or “fullness” with the fiber addition and tend to eat less if given free access to food. The same response in cat and dog subjects suggests that fiber has the same satiation effect.
During the course of a normal meal, the stomach and intestines fill, causing distension or stretching of the walls of these organs. Distention causes a release of stomach and intestinal hormones into the blood, which travel to the satiation center of the brain, triggering the “stop eating signal.” Adding fiber increases meal volume without adding significant calories and hastens the satiation effect. The feeling of fullness decreases food consumption and reduces calorie intake. Weight loss experiments have confirmed the effectiveness of this strategy.
The Problems
A 50 percent reduction in calories could be too severe. Putting an animal on such a program without veterinary supervision or preliminary lab work could result in serious medical problems for any age group and especially those with undiagnosed medical conditions (liver problems, kidney problems, heart problems, diabetes, hypothyroidism, etc.).
Regular food is inappropriate for weight loss patients. Although weight loss patients are fed the calories appropriate for their ideal target weight, they still need amino acids, fats, vitamins and minerals for their present weight.
Dieters also need extra protein to reduce the amount of muscle that is lost during dieting. Pet foods are formulated to deliver essential nutrients based on standard calorie consumption. If calories are restricted than so are essential nutrients. That is why dieting animals need special formulations, commercial or homemade, that are heavily fortified with extra protein, essential amino acids, and essential fats, vitamins and minerals in order to compensate for the reduced calorie intake. Adding green beans to a regular food diet could result in significant nutrient deficiencies, especially if the dieting was prolonged. This malnutrition is exacerbated by the fact that high dietary fiber interferes with the digestion and absorption of some essential fats, calcium, zinc and iron.
As we have discussed in previous blogs, body metabolism changes as the body loses weight. The calorie intake that induced the first ten pounds of body weight may be too much to achieve the next ten pound loss because the body has adapted and can maintain weight on fewer calories. A 50 percent reduction in calories may still be too much food for a severely overfed animal to achieve ideal weight; a supervised multi-stage weight loss program would be more successful.
These metabolic adaptations can also cause weight regain when dieters are weaned from green beans and resume eating normal food. The adaptations that occur during dieting are so dramatic that studies in dogs that were induced to obesity and then successfully dieted could be induced into obesity again with fewer calories and in less time. Maintaining higher fiber content in post-weight loss diets has been shown to be effective for humans, cats, and dogs in managing weight after dieting.
My Take
I use green beans as part of my weight loss program. I find my weight loss patients like them and the beans reduce begging behavior between meals. I have also found that owner compliance to the program is better if they can use green beans as treats. Few have complained about the increased gas production and flatulence. However due to the problems cited above, green beans are not substitutes for comprehensive weight loss programs. Think of weight management as a chronic condition that requires constant monitoring like heart or kidney disease. Find a veterinarian that shares your concern to work closely with.
Sadly, I will admit this will not be an easy task, but be persistent. Weight loss is too serious to go it alone with only the help of Dr. Google.
Dr. Ken Tudor
Image: IMG_4240 by Shelly Couvrette / via Flickr