Is The Alkaline Diet Good For Weight Loss?

Is The Alkaline Diet Good For Weight Loss?

Each year we are subjected to the latest health craze or fad diet. These are often endorsed by celebrities or alternative medicine advocates.

That doesn’t necessarily mean that they work though. But get the marketing right and it’ll sell for a while until people begin to realize that their over-hyped way of eating just isn’t sustainable.

Could the alkaline diet different and could it be the way forward? Is it a healthy and sustainable way of eating, or is it just another passing fad?

Let’s find out…

What is The Alkaline Diet?

In simple terms, the alkaline diet is a way of eating that emphasizes non-acidic foods over acidic ones.

Otherwise known as the acid ash diet or the acid alkaline diet, the main premise of this way of eating is that you base your food choices around those that affect the acid levels of your blood.

Ancestral data suggests that once upon a time humans consumed a diet that of around 87% alkaline foods. This diet is based on the notion that the modern, western diet reflects a mismatch between nutrient composition against a more optimal way of eating [1].

Whilst there are a few different versions of the diet, the main recommendation is that you aim for around 80% alkaline food choices and the remaining 20% from acidic foods.

It is a versatile diet that suits vegetarians as well as vegans too. And at face value doesn’t seem as strict or as rigid as some other approaches.

Acid and alkaline

You might have to cast your mind back to school for this one, but acidity is measured using the potential of hydrogen or pH scale. It is a way of measuring how acidic or alkaline something is.

pH uses a 0 to 14 scale where 0-7 is acidic, 7 is neutral and 8-14 is alkaline.

It is recommended when you follow the alkaline diet that you monitor your urine pH using test strips. These allegedly give you an idea of how well you are sticking to the diet.

But what it seems to dismiss is that different parts of the body run best at different pH levels.

For example, your stomach however has a pH of around 2-3. This is due to its high hydrochloric acid content which is needed to break down and digest food.

Human blood is typically neutral – around 7.4 – so it’s neither acidic or alkaline. Your body has a precise mechanism for maintaining this called the blood acid base and it doesn’t shift much at all. This involves the kidneys as well as the liver and lungs.

Urine however can fluctuate. In the morning it can be a slightly acidic 6.5 but becomes more neutral as the day passes. During the night it becomes slightly alkaline, probably due to the fact that no food is consumed whilst asleep.

Which Foods are Alkaline?

When we eat food we have to digest it into usable parts so that we can absorb the good bits and get rid of the bad bits. When we ‘burn’ these foods for energy we are left with a residue or ‘ash’ which is then ejected from the body in the urine.

The pH of this ash is then measured to see whether the food is alkaline or not.

Alkaline Foods:

  • Vegetables and fruits
  • Nuts
  • Legumes – lentils, beans etc.

For each of these categories consists a number of different foods. Cabbage, spinach, kale, carrots are all alkaline vegetables. Fruits include lemons, limes and grapefruits. Additionally, green tea and water also provide an alkaline ash effect.

Foods to Avoid

  • Animal products – meats, dairy, eggs
  • Refined rains
  • Soda and sugary foods
  • Fast food and pre-packaged meals
  • Tobacco, caffeine and alcohol

One possible benefit of this diet is that you don’t need to count percentages of each group as such, but instead use a more common sense approach to aim for the 80:20 rule. This could make it easier for you in comparison to calculating macronutrient ratios like with other diets.

What Are The Reported Benefits of the Alkaline Diet?

Many proponents of the alkaline diet suggest that because the modern western diet is far too acidic it is causing health issues such as cancer, heart disease and a range of neurological disorders.

The truth is though that whilst your urine pH might shift slightly based on your food choices, your blood pH won’t change at all.

The physiology of the blood acid base is quite clever – eat food and your pH goes down. The excess acid is then quickly excreted in the urine (which then becomes temporarily acidic) and your blood levels don’t change. Once excreted your urine becomes neutral again. Simple.

Cancer Risk

Poor food choices can increase the risk of cancer. This is well evidenced. A lack of fiber and a diet based on junk food can increase the risk of cancer tremendously.

The idea is that cancer cells grow faster in an acidic environment so by maintaining a more alkaline blood pH cancer risk is decreased. Some have even stated that it can cure cancer.

As we know by now though, blood pH can’t be manipulated. And whilst cancer cells do grow quicker in acidic environments, many experts suggest that it is the cancer itself that causes acidity, not the other way around.

A large review published in Nutrition and Metabolism [2] found no link at all between diet-induced acidosis and cancer. It also stated that there are no other studies to date that have found a potential link either.

Bone Health

Another proposed benefit of alkalizing foods is that they can maintain bone health, particularly in the elderly.

Bone related diseases such as osteoporosis are caused by an accelerated loss of minerals and advocates of the alkaline diet suggest that maintaining a higher pH helps to keep your bones strong.

Again though, this neglects the fact that the kidneys, as well as the liver and lungs work hard to maintain a constant blood pH.

It also dismisses the fact that acidity is not the primary cause of osteoporosis.

To date you’ll struggle to find any actual clinical research to suggest that alkaline diets boost bone health. If anything it is quite the opposite [3].

Blood Acid Disorders

In healthy individuals your blood acid base won’t change. But there are certain disorders where blood pH can drop dramatically – and this can be life threatening.

Diabetic ketoacidosis for example is where blood pH drops to a dangerously low level because of a lack of insulin. It is caused by metabolic complications relating to diabetes and can be deadly if left untreated.

Blod acidosis can also be caused by respiratory complications where there is a build up of carbon dioxide in the bloodstream which is toxic and potentially fatal. There’s a reason why if you hold your breath you have to eventually breath!

But for those who do not have respiratory or metabolic disorders, there is no need to worry about blood pH changes.

Key Point: Reports that the alkaline diet can reduce the risk of, or even cure illnesses is just a myth.

Can The Alkaline Diet Help You Lose Weight?

In order to lose weight you have to be in a calorie deficit. This means that you have to eat less calories than you burn off each day. By doing this your body is happy to use stored fat as an energy source.

If you’re not in a deficit you won’t lose weight. And that’s regardless of the types of food you eat. No matter how healthy your food choices are, if you eat too much you’ll put weight on.

As diets go, the alkaline diet is probably one of the healthiest ones to follow as it forces you to eat nutrient-rich foods and be conscious about overall choices. Fruits and vegetables in particular are filled full of vitamins and minerals that help to optimize the way that your body works.

It can definitely help you achieve a calorie deficit as long as you monitor overall energy intake.

The truth of the matter is though that nothing you eat will change your blood pH that much. This means that any weight loss isn’t down to any alkalizing effect – just that you’re maintaining a calorie deficit.

The question is though whether the diet is sustainable. Cutting out meats and other animal products can be difficult and many foods that you may like to eat on a regular basis are a no go on this diet.

And of course, the best diets are the ones that you can follow with little effort. 

Summary – Can The Alkaline Diet Boost Weight Loss?

Making healthy choices is key to successful weight loss. And regularly eating fruit, vegetables and other nutrient-rich foods helps you achieve this.

Whether the alkaline diet can support weight loss because of changes to blood pH or simply that it helps you achieve a calorie deficit is another matter though.


  1. Sebastian, A et al. Estimation of the net acid load of the diet of ancestral preagricultural Homo sapiens and their hominid ancestors. Am J Clin Nutr. 2002; 76(6): 1308-16
  2. Robey, IF. Examining the relationship between diet-induced acidosis and cancer. Nutrition & Metabolism. 2012; 9: 72
  3. Pedone, C et al. Quality of diet and potential renal acid load as risk factors for reduced bone density in elderly women. Bone. 2010; 46(4): 1063-7