Should You Try an Alkaline Diet for Weight Loss? An RD Answers

There is no shortage of diets to choose from, but one has been gaining traction in recent years, in large part thanks to its vast array of purported health benefits, including the fact that it promotes weight loss, detoxification in the body, and helps crush sugar cravings. The alkaline diet was first made famous by the late Dr. Sebi, who is credited with pioneering eating a plant-based diet (which is the basis for the alkaline diet) as a healthy lifestyle choice. The idea behind the alkaline diet is that eating certain foods can have an effect on our body's pH balance in the blood, which can help lower inflammation, help keep your cells healthy, and combat serious diseases and conditions including chronic pain.

When we eat food, our metabolism breaks it down to be used as energy. The alkaline diet is based on the theory that there is leftover metabolic waste from the food we eat, which can have either an alkaline, neutral, or acidic pH effect on the body. It’s believed that this residue or “ash” can affect our body's pH levels. When this “ash” is acidic, it’s believed to increase your risk of various illnesses and diseases, where alkaline ash is thought to be protective.

How is pH measured: pH levels fall on a range, starting at 0 and going up to 14. Acidic foods range from 0 to 6.9, if food is neutral it’s at 7.0, and basic or alkaline foods range from 7.1 to 14.0. Our body is naturally alkaline, with a pH of between 7.36 and 7.44 according to the Clinical Journal of the American Society of Nephrology. Certain parts of our body can have completely different pH, though, with our stomach being very acidic at a pH of 1.35 to 3.5.

Our diet doesn't affect pH balance of our blood–or only in tiny, momentary increments–since it is regulated by the kidneys, which removes waste from the body by flushing it out in your urine, in what's known as acid-base homeostasis. Our pH balance in the blood needs to be kept constant by our kidneys and lungs, which exhale CO2 and then bring fresh oxygen into the blood. (When our pH balance in the blood is thrown off it requires medical attention since it's a sign something is seriously wrong.) However, the food we eat does impact how much acid is secreted in our urine due to how much the kidneys need to get flush it out due to the foods we eat. That's the measure of how healthy or unhealthy our diet is.

Some foods can have an acidic pH but aren’t acid-forming foods once your body is done metabolizing them. Acid-forming foods are the ones that leave behind that acidic “ash.” Take citrus fruits, such as limes, lemons, and grapefruit, for example. They naturally have an acidic pH, but when eaten they don’t create acid in your body.

Foods have different potential renal acid loads (PRALs), according to a 2019 meta-analysis published in PLoS One. High PRAL foods tend to be acid-forming foods, which causes the kidneys to do more work to keep a balanced pH. The same analysis states that a high PRAL diet could lead to issues such as high triglyceride levels and obesity.

Foods that increase acid loads can change the urinary chemistry, according to a review study published in the Journal of Environmental and Public Health. Urinary magnesium levels, urinary citrate, and pH are all decreased while urinary calcium, uric acid, and phosphate are all increased which can increase the risk of kidney stones.

High potential renal acid loads include:

Although you are not going to change your blood's pH with what you eat, it may be beneficial to limit or completely eliminate the foods that are considered acid-forming. Opting for a diet that is low in PRALs could benefit our kidneys, heart, and bone health, a 2018 review published in the Journal of Renal Nutrition states.

Another study from Osteoporosis International also found a small association with an alkaline diet and the improvement of muscle mass in healthy women that was independent of their age, physical activity, and protein intake. The researchers state, “although protein is important for the maintenance of muscle mass, eating fruits and vegetables that supply adequate amounts of potassium and magnesium are also relevant.”

A downfall is that some foods deemed acid-forming are actually important parts of a healthy diet. Grains are packed with beneficial nutrients such as B vitamins, fiber, antioxidants, and various minerals. There are a few grains that have an alkalizing effect, which includes millet, quinoa, and amaranth. If your love of rice runs deep and you don’t want to give it up, a 2014 article published in Advanced Chronic Kidney Disease also states that adding fruits, vegetables, and other alkaline foods to certain grains can help reduce their acid load.

If you’re interested in trying the Alkaline diet, a good starting point would be to transition over to plant-based eating. Many of the foods that carry a heavy acid load are predominantly animal products and ones that are more basic (alkaline) are those of plant origin.

A 2017 study published in Plant Foods for Human Nutrition wanted to determine how adherence to a vegan diet (extremely low in PRALs) could benefit our health and avoid the complications that may come along with a high PRAL diet. The study compared PRAL changes and urine pH in omnivores who followed a vegan diet for either 2, 3, or 7 days over the span of a week. The 7-day group followed the diet consecutively where the 2 and 3-day groups followed the diet for evenly spaced days. The outcome found that all groups had a significant decrease in dietary PRAL scores which can improve metabolic diseases such as insulin resistance and cardiometabolic risk.

Even a few days per week of a plant-based diet could improve dietary PRAL scores and therefore lower disease risk.

Bottom line: The Alkaline diet will not change your body's overall pH, but choosing foods that have a lower renal acid load could benefit your health in the long run.