Principle Physiotherapy

It seems that every few years there is a new or “better” way to lose weight. Who knew that a diet would come to the fore that promotes eating higher fat to lose fat? The term ketogenic diet is thrown around a lot but what is the science behind it, why has it become so popular, and what are the health consequences of taking up this way of eating?

What does ketogenic mean?
The term ketogenic comes from the name of the chemicals produced when fatty acids are broken down in excess. These chemicals or ketone bodies are produced in the liver when carbohydrates are so scarce that energy must be obtained from preferentially breaking down fat. Production of these compounds is called “ketogenesis”, and this is necessary in small amounts.

What is ketosis?
When we look into the terms used by those promoting the ketogenic diet, the term a state of “ketosis” is used to describe what is optimal to burn fat. When excess ketone bodies accumulate, this abnormal (but not necessarily harmful) state is called ketosis. If this reaches a harmful level the body’s PH can become dangerously acidic. This is called ketoacidosis. This is an extreme state and is most often associated with Diabetic Ketoacidosis, when a diabetic’s body runs out of insulin. Ketosis can take days or weeks and is only achievable if your carbohydrate intake is as low as 5-10% of your total calorie intake. To put this into perspective the UK government’s dietary reference value for carbohydrates is 50% of your daily food energy intake1 .

Why is the ketogenic diet so popular?
The ketogenic diet consists of low carbohydrate, moderate protein and high fat. It is an extreme form of calorie restriction and therefore initial weight loss is often seen. Furthermore fats in food contribute multiple sensory aspects of eating including making food tender, stimulating appetite, giving food taste and smell, whilst also helping us to feel full and satisfied after eating. Therefore a diet made of primarily fat can, in theory, be extremely enjoyable. You may have also seen ketones being sold as a supplement to help with weight loss. These artificially elevate levels of ketone bodies in the blood helping to, in theory, speed up ketosis.

What does the evidence say?
Despite agreement that, yes there is an initial rapid weight loss on keto or low carb diets, this is often due to excess body water loss2 . Long term this is not the case and a lack of carbohydrates can often result in brain fog, and a lack of energy. Carbohydrates are our body’s main source of energy; are vehicles for important micronutrients and phytochemicals; and key for gastrointestinal integrity and function. They should not be demonised. Studies have shown that adults with obesity showed a greater body fat loss when dietary fat was restricted as opposed to carbohydrates, calorie for calorie3 . This is not to say fat is bad, however an over consumption of animal-derived protein and fat sources (beef, lamb, pork etc.) has been associated with higher mortality. It may therefore be beneficial to  increase your plant-derived fat intake from sources such as nuts, vegetables and whole grain bread4 (get some fibre in there too. Read about why fibre is important here https://rhitrition.com/why we-all-need-fibre-in-our-diets/). Fat is important for many metabolic processes in our bodies and are converted to other compounds such as hormones, bile and vitamin D, as needed. More specifically omega 3 fatty acids provide many health benefits with regard to their cardiovascular disease prevention properties5 , anti-inflammatory effects and are directly involved in visual and neural cell development. However studies are not in complete agreement and much more research needs to be done on the subject6 . It is important that we focus on a balance, and that we do not demonise an entire food group.

Good sources of fat to include in your diet:
Having fat present in your diet in huge amounts may not be helpful for your long term health or possibly sustainable weight loss. However foods that provide fat with micronutrient health benefits are a great addition to a healthy balanced diet.

● Nuts: brazil nuts not only provide fat, but are a great source of selenium helping you to fall asleep (toxic in large doses, so one brazil nut, or 55 micrograms, is the recommended daily intake) 7 .

● Whole-grains: whole wheat pasta, brown rice, oats and even popcorn. They provide the added benefit of fibre, B vitamins, iron and folate.

● Chia seeds: These little black seeds from south america are not only a good source of omega 3s, they are rich in protein, fibre, calcium and zinc

● Dark Chocolate: Now this is a controversial addition. It is important to note that we are talking about 70% or more dark chocolate. This high percentage cocoa solid delight is rich in plant chemicals called flavanols. Flavanols have been shown to help relax blood vessels, improving blood flow, thereby lowering blood pressure in healthy individuals8 . 1-2 squares (6 grams)9 of dark chocolate daily is also rich in iron, zinc and magnesium . Studies are observational, and as with everything, must be consumed in moderation, as part of a balanced diet.

● Hemp seeds: This is a weird one to most. But these crunchy seeds can be found in most health food stores. They are a great source of omega 6 fatty acids, which should be consumed at a ratio of 1:1 with omega 3s. They are also a great source of protein, vitamin E and potassium. Hemp seeds can be sprinkled on pretty much anything!

● Avocado oil: We all know that avocados are good for you but what else do they provide other than a great topping to toast. The oil can be used for cooking, who knew?! Really high in antioxidants, the oil from these green fruits also has a high smoke point and is therefore safe for baking, roasting, sautéing and frying.

References
1.https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachm
ent_data/file/445503/SACN_Carbohydrates_and_Health.pdf

2. http://europepmc.org/article/PMC/333231

3. https://pubmed.ncbi.nlm.nih.gov/26278052/

4. https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30135-X/fulltext

5. https://pubmed.ncbi.nlm.nih.gov/18408140/

6. https://www.cochrane.org/news/omega-3-fatty-acids-primary-and-secondary-
prevention-cardiovascular-disease

7. https://pubmed.ncbi.nlm.nih.gov/23992533

8. https://pubmed.ncbi.nlm.nih.gov/14654748/

9. https://pubmed.ncbi.nlm.nih.gov/20354055/