Episode 20: What we’ve learnt from the ketogenic diet and why you shouldn’t break up with carbs

KETOGENIC DIET

What is it?

• Very low-carb, moderate-protein and high-fat diet. It typically contains 75% fat, 20% protein and only 5% carbs.
• 20g CHO per day  - Eg 1 apple + ½ cup peas + 4tbsp milk  OR sk latte + ¼ cup chickpeas OR 1 small banana   OR 1 small slice sourdough bread 

Does it work?

• Weight loss - very low CHO intake leads to increased fat metabolism for ketones. 
• The rise in fat burning does not necessarily mean loss of fat stores given the intake of fat in the diet has significantly increased. 
• Studies suggest that the overall body fat balance is equal if not in favour of fat storage!
• CHO insulin model - reduced insulin so less fat stored. Good in theory but a very intensive $40 million study of 17 men were admitted to metabolic wards for intensive monitoring for 2 months - one month high carb, one month ketogenic. Matched calories on both. Subjects spent 2 consecutive days each week residing in metabolic chambers to measure changes in exergy expenditure and underwent DEXA to measure body composition. The study found that the subjects lost more body weight on the ketogenic diet, but rate of fat loss was 50% slower on the keto diet and instead the on the ketogenic diet that subjects lost more water weight and suffered more LBM (muscle protein) catabolism. Interestingly, this was a study funded to explore their hypothesis which was the opposite!

https://academic.oup.com/ajcn/article/104/2/324/4564649

• Epilepsy that is refractory to medication - often as third or fourth line therapy. 
• Cancer - theory based on Warburg effect that cancer’s preferred fuel source is sugar and that by reducing CHO intake we can deplete tumour tissue of the glucose required for tumour cell metabolism. Unfortunately, that’s the case of most of the healthy cells in our body. Sugar fuels everything and cancer can feed off everything, including ketones. 
• As it stands, there are no clinical trials demonstrating a benefit of a ketogenic diet in cancer patients. Studies underway exploring the ability to slow the growth of certain brain tumours. 
• What our best practice guidelines do specify though is that while it may be difficult to induce tumour responses with a ketogenic diet, this does not argue against preferring fat to supply energy to patients with advanced cancer and inflammation-induced insulin resistance - so more avo, nuts, seeds and extra virgin olive oil and less refined sugars. 

DRAWBACKS

Gut Health

• Our carbohydrate sources in our food supply don’t just provide energy. Think about a chickpea. Yeah it’s got carbs, but it’s also loaded with fibre, protein, folate and iron.
• One important factor that we miss when we significantly restrict CHO intake is fibre, prebiotics and the impact on our gut. 
• Bowel cancer risk + digestive health 

Diabetes (T2DM)

• Some proponents suggest ketogenic diet to manage diabetes
• Managing the symptoms - high blood glucose levels - rather than the cause - insulin resistance (may be as a result of being overweight, lack of PA + poor dietary patterns).
• Ketogenic diet has been associated with development of NAFLD and associated hepatic insulin resistance in mice. This can induce or worsen insulin resistance
• Some human studies show an initial improvement in insulin response on a ketogenic diet but this seems to only be temporary - which makes sense given the KD is reducing the symptoms (high blood glucose levels), but may actually be worsening the cause (fatty deposits in the liver and cells)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5452247/

Cardiovascular disease 

• KD are often high in saturated fats
• Breakfast of egg, bacon, bullet coffee; lunch and dinner of M/C, small amount of veg and some cream for dessert...it’s no surprise that this will take its toll.  
• The majority of animal studies suggest that when KD are rich in saturated fats they negatively impact blood lipid profiles and cardiovascular disease risk 
• In human studies, there are really varied results, often depending on the length of time subjects are followed and the profile of their fat intake.
• Some studies highlight that even in cases where KD show a reduction in total and LDL cholesterol, these were significantly more reduced with a high-protein medium-carbohydrate diet than with a KD

Compliance

• Hard! 
• Even in retractable epilepsy compliance may drop to 50% after a few months. For epilepsy this is disappointing for ability to gain disease control, but for the general population this could be a protective mechanism...children have died from scurvy and selenium deficiency and the long term implication for cardiovascular and gut health just might not be what your human control centre wants. 
• 20g CHO per day 
• Eg 1 apple + ½ cup peas + 4tbsp milk OR 1 small banana  OR 1 small slice sourdough bread 

Exogenous ketones

• Introducing ketones from external source can mean you will test positive for the presence of ketones - suggesting you're in “ketosis”. Simply because the ketones exist doesn’t mean you’ve gone through the pathways to get there.
• The presence of ketones signals to the body that you’ve been making them, and therefore may slow or even stop it’s own production of ketones from fat stores. This is a particularly important safety mechanism because ketone blood levels become too high, your blood can become dangerously acidic.
• Therefore, taking exogenous ketones may prevent body fat from being used as fuel, at least in the short term
• One benefit of exogenous ketone esters or slats - often taken as a drink - is that they may reduce circulating levels of our hunger hormone ghrelin. One study of 17 people found reportedly lower levels of hunger after taking the ketone drink. But only effective after a fast, not after a meal
• You’ve also got to bare in mind that ketones contain calories. A single serving of exogenous ketone salts typically contains less than 100kcal or 420kJ, but to maintain a state of ketosis, you’ll need several servings each day = could add up to the energy in a main meal! 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5813183/

• Bulletproof coffee/ MCT oil - contains medium-chain triglycerides, can help keto dieters add more fat to their diets and stay in ketosis. It’s digested more rapidly than traditional fats but can have digestive side effects and again a caloric load.

Action

• If you’re going keto, prioritise unsaturated fats - avo, nuts, seeds, EVOO
• Make your carbs count
• Don’t rely solely on the white ones (white bread, white rice, white potatoes, white pasta)
• Choose CHO sources that offer something else: fibre, protein, vit, min 
• Eg 
  • Fibre: wholegrains such as barley, bulghur, freekeh, spelt, quinoa, oats, legumes, peas, corn, pulse pasta  
  • Protein: legumes, ricotta or cottage cheese
  • Vitamins: sweet pot, peas, corn
  • Minerals: greek yoghurt, milk, ricotta, cottage cheese

 

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