A dietitian’s perspective
I get asked quite often whether vegans can do the keto diet and if it’s healthier than the meat based version. To answer this question, we need to look at exactly what it is.
Keto nearly always gets confused with your standard low carb diet, but it has specific features that differentiate it from other less extreme diets. To be truly keto a diet has to be very high in fat, moderate in protein, and very low in carbohydrates . It’s had many predecessors – most notably Atkins which fell off the radar after Dr. Robert Atkins was found to have severe heart disease when he passed away. in 2003.
Fundamentally, Keto aims to restrict carbohydrates to 5-10% of calories while 70-80% of calories come from fat. The current dietary guidelines recommend 20-30% of calories from fat, and maximum 10% of calories from saturated fat. This decreases to maximum of 7% if you have risk factors for cardiovascular disease such as abdominal overweight/ obesity, high blood pressure, diabetes, high cholesterol or a family history of these.
By definition Keto is a fad diet due to it’s intentional restriction of carbohydrate foods.
How keto works
Depriving the body of fuel (carbs) for long enough puts the body into a state of ketosis. This means it’s forced to break down fat for energy instead of glucose, and ketones are a by-product of this. Essentially, it utilizes the body’s starvation response. This process is is what keeps the brain alive and alert so that it can find food.
Why it’s such a big deal for weight loss is because of the effect that ketones have on appetite. Basically, ketones shut off your normal hunger signals and boost your energy and focus, which is a dream for weight loss because it’s easy to eat way less food.
However, unfortunately, if something seems to good to be true – it usually is. The initial rapid weight loss that people experience on keto is fluid, sodium and glycogen that come from your liver and muscle…and not body fat. What’s even worse is that such rapid losses in fluid can also cause electrolyte derangement which feels like you have the flu (it’s actually called “keto flu”).
Traditional keto diets emphasize animals foods because they don’t contain carbs – and it’s and added benefit that they tend to be high in fat. Plant foods such as legumes, whole grains, vegetables and fruit are restricted or totally avoided because of their relatively high carbohydrate content.
However, there are some low carb diets that are plant based or vegan – for example Eco Atkins.
Benefits of ketosis
The rapid weight loss experienced on a keto diet is mostly water, glycogen and electrolyte losses and not body fat, at least in the early stage. As with any body fat loss, true weight loss happens by eating fewer calories – which appetite suppression from ketosis supports. Any type of fasting, including VLCDs, will put you into ketosis.
Staying in ketosis for long periods of time is next to impossible for most people, and your appetite returns as soon as you eat carbohydrate. Therefore, as is the case with any unbalanced diet, keto is hard to stick to, making weight loss difficult to maintain in the long term. Perhaps most importantly, the metabolic benefits of ketosis are reduced when you switch in and out of it.
Anecdotally, I am yet to meet a client who has maintained weight loss achieved through a keto/ low carb diet. However, that is not to say it can’t help to reset unhealthy eating patterns – especially with the benefit of temporarily reduced appetite and keen motivation.
Improved blood sugar control
Keto diets reduce blood glucose levels because they restrict carbohydrates, reducing insulin requirements. However, high fat consumption also causes a insulin large spike, leading to worse insulin resistance. Diets high in saturated fat also increase the risk of developing fatty liver disease, something people with diabetes are at increased risk of. So the apparent short term improvements in blood glucose control may not be as good as they seem at first.
Treatment resistant childhood epilepsy
A keto diet changes the microbiome, which has been shown to improve/ reduce seizures in epilepsy. However this change in gut flora has not been shown to have positive effects in the general population.
Health risks of keto diets
Most of the risks associated with keto diets are due to the high intake of animal protein. Examples of these include:
- Animal protein-induced kidney damage
- Kidney stones
- Heart disease
- Bone loss as a result of hypercalciuria
- Increased risk of death from all causes
- Non-alcoholic fatty liver disease
There are other concerning health impacts associated with high saturated fat intake. These include:
If a person is overweight, even modest weight loss will improve blood glucose control. Since people initially lose weight on keto, this is a benefit. Also, limiting glucose in your diet means less glucose in the blood after meals – also good. But eating fat and protein cause insulin -not glucose- to spike. A lot. In fact, dietary fat causes a more insulin to be released than glucose. Since the body is no longer burning glucose for fuel, cells become resistant to insulin and handle glucose less effectively in the future. Insulin resistance is one of the contributing factors of type 2 diabetes and metabolic syndrome.
Decreased athletic endurance
One study showed athletes who were fat adapted had decreased endurance capacity during high intensity exercise. And further, their efficiency of carbohydrate burning remained reduced, even after cycling out of ketosis.
“Keto breath” is a common complaint for people in ketosis. This is because consuming too much protein creates lots of ammonia, which causes bad breath. This may be a consideration if you work in close range of people.
High LDL cholesterol
Because animal based keto diets are typically high in saturated fat, keto diets may raise LDL cholesterol. This is known as keto-induced hyperlipemia, and some doctors may offer to treat this prophylactically with statins. Other studies have reported reduced cholesterol, however, the long term effects of keto on heart disease remain to be seen .
The body needs plenty of fibre to move the digested food through your colon and beyond. Fibre is only found in plants, so since traditional keto diets restrict plant foods, constipation is common.
What about vegan keto?
The benefits of whole foods plant based diets are well established for metabolic syndrome, but it’s unclear whether these benefits will hold if the diet was very high fat.
The other concern is restriction of legumes as most are too high in carbohydrates for vegan keto. Protein sources are limited to tofu, soy milk, lupin, protein powder, chia seeds, hemp seeds, flax seeds, nuts and nut butters and certain varieties of plant based meat products. Legumes are among the healthiest foods available, and are one of the primary sources of protein on a plant based diet. Removing them greatly reduces diet variety and diversity – which are extremely important for satisfaction and nutritional adequacy.
The good news
Keto can be done in plant based way – and there may be some benefits when compared to regular keto.
The plant based fats that feature in a vegan keto diet are: avocados, coconut products (milk, yogurt, oil and cream), olive oil, seeds and nuts/ nut butters. Apart from coconut, all of these fats are unsaturated which is much better for your LDL levels. They also burn better as a fuel than saturated fats do and may help to prevent accumulation of abdominal fat (i.e. the harmful, metabolically active fat). As always on a vegan diet, your omega 3 comes from flaxseeds, chia seeds, hemp seeds, soy foods and algal DHA supplements.
As vegan keto is based on plants, there is plenty of fibre to keep your gut (and your microbiome) healthy.
I personally don’t recommend a vegan keto diet unless it’s medically indicated (i.e. resistant epilepsy in children). This is due partly to the restriction of extremely healthy foods, especially starches, legumes and wholegrains, which are cornerstones of a healthy diet. It may not be possible to meet your nutritional requirements without these foods. It is practically impossible to maintain ketosis for long periods due to intense carbohydrate cravings. I’m troubled by the metabolic effects of switching in and out of ketosis – such as insulin resistance and impaired glucose tolerance. I’m keen to see what the research shows in future about the long term health effects of plant based keto…but we are not there yet.
If you do decide to try a plant based keto diet, ensure that you are taking a B12 supplement. It’s a good idea to speak to a dietitian to ensure that you don’t end up with nutritional deficiencies.