The theory behind the diet is that when your body metabolizes food, you produce byproducts that are either acidic or alkaline. According to Self, eating acidic foods is unhealthy, because it makes your body's pH level too acidic, thus making it more vulnerable to disease.
The pH level measures how acidic or alkaline something is. It is measured on a scale of 0 to 14, with 0 being totally acidic, 14 being totally alkaline, and seven being neutral. Your stomach, for example, is very acidic, because stomach acid is needed to break down food, while your blood remains quite constant with a slightly alkaline level (unless you're extremely ill). Meanwhile, the pH of your urine changes constantly, reflecting what you eat.
Which foods are encouraged?
You'd think that because lemons are acidic, they would be avoided under the Alkaline Diet's guidelines. But, according to Self, it's actually considered to be alkaline, since they're broken down into an alkaline substance in our bodies. It all comes down to how foods affect the acidity of your urine.
If you want to follow the diet strictly, U.S. News & World Report says that 80 percent of your foods and beverages should be alkaline-forming and only 20 percent should be acid-forming. Many people are less strict and opt instead for a ratio of 60 percent alkaline-forming to 40 percent acid-forming.
The following foods are encouraged under the Alkaline Diet:
- Fruits (natural, not sweetened or dried)
- Some nuts, such as almonds and chestnuts
- Some seeds
- Some legumes (beans and lentils)
Foods to avoid
Alkaline diet guidelines discourage consumption of the following foods and beverages:
- Red and processed meats
- Dairy foods
- Fried foods
- Fatty foods
- Breads high in yeast and wheat products
- Sugary snacks
- Sugary drinks
- Many condiments
What's the verdict?
Many experts (including those in U.S. News & World Report, Healthline and Self) believe the diet may be able to help you lose weight and improve your health. But that's because you'll be eating more fruits and vegetables and less red meat, sugary snacks and processed foods − not because of any claims about acidic or alkaline foods.
There's no evidence that eating acidic or alkaline foods affects your weight or makes you any more or less prone to disease, experts say. Acidic or alkaline foods don't change the pH of your blood, which stays within a very narrow range no matter what you eat. And these foods change the pH of your urine only temporarily.
Most dietitians encourage eating lean meats, dairy and whole grains, which goes against their exclusion in alkaline diet.
Additionally, many of the experts cited n Healthline and Self, state that, like many restrictive diets, the alkainline diet may be impractical and difficult to follow over the long-term.