**5. Low-carbohydrate high-fat (LCHF) diet**

Low-carb high-fat diets are gaining popularity in Europe, especially Scandinavia, having originated in Sweden. The LCHF diet has been popularised by Swedish GP Dr Annika Dahlqvist, who has been recommending a low-carb high-fat diet to her patients for some years now. As this was a somewhat revolutionary concept, she had her opposition. The story goes that she was investigated by the Swedish Health authorities for any wrong doing but investigations cleared her based on their findings that her methods were scientifically sound [48].

carbohydrate is defined as less than 130 g per day, whereas 'very low' carbohydrate is less than 50 g per day [60]. Although individual responses vary, ketosis usually occurs in people who restrict their carbohydrate intake to below 20–50 g/day with some degree of protein

Low-Carbohydrate High-Fat (LCHF) Diet: Evidence of Its Benefits

http://dx.doi.org/10.5772/intechopen.73138

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Contrary to what many people think, most LCHF diets are not high in protein. In fact, for every 100 g of protein consumed, 56 g of glucose can be produced [61]; thus, having too much can affect blood glucose and undermine the principle of LCHF. Protein can also directly stimulate insulin resistance. Moderate protein consumption, 2–3 portions per day, is therefore usually recommended. Protein can also increase satiety, i.e. it can help you to feel fuller.

When carbohydrate is restricted, it is important to increase the levels of fat consumed—a low carbohydrate AND low fat diet inevitably lead to hunger. Fat should be consumed to satiety. Healthy natural sources of fat include olive oil, butter, grass-fed meats, eggs and dairy products. There is no need to be afraid of fats, including saturated fats and cholesterol, though trans-fats and hydrogenated or partly hydrogenated vegetable oils (often found in

A LCHF diet should also include a lot of green leafy vegetables, although consumption of starchy vegetables (such as potatoes and other root vegetables) and fruit should be limited

According to the Banting diet eating plan [62], foods that can be consumed liberally on the LCHF diet include dairy like natural yoghurt, cheese, cream, butter, along with meat, fish, eggs, vegetables and olive oil. Foods that can be consumed in moderate amounts are bean and lentils, nuts, almonds and sunflower seeds, fruits (not dried fruit), chocolate with a high cocoa quantity (65–90%), sausages and moderate amounts of alcohol. Foods to be avoided are potato; rice; bread; flour and corn-based products; cereal-based products, such as pasta, pastry, biscuits and breakfast cereals; sweets and cakes; sugary drinks; margarines and omega-6 based oils such as corn, sunflower, safflower, soybean and peanut oil. More information about the LCHF diet can be found in the book, 'Diabetes, No thanks' [63] description of one man's journey from his diagnosis of diabetes to controlling his diabetes

Increased satiety, allowing a lower energy intake without hunger and a specific metabolic advantage have been proposed to explain how LCHF diets produce weight loss, despite an

A recent systematic review compared weight loss between participants on 'LCHF diets' and 'low fat balanced diets' [64] but excluded all trials that were not isoenergetic. Although the original study did not find any differences in weight loss between the different diets, a reanalysis [64] of the same data found a small but significantly great weight loss on the lower car-

**7. Mechanisms for weight loss on the LCHF eating plan**

increased consumption of energy-dense 'fatty' foods.

restriction (nutritional ketosis).

junk foods) should be avoided!

with the diet alone.

bohydrate diet.

due to their higher carbohydrate content.

As the name suggests, the diet suggests eating high fat and low carbohydrate foods. The LCHF diet is different to the Atkins diet as there are no 'stages' to work through, so the diet can be followed indefinitely. People are encouraged to eat full fat versions of dairy food and fatty meats with fat on rather than removing it.

The diet, because of its low requirement for insulin, has been recognised by the Swedish government as being suitable for people with type 2 diabetes and as helpful to individuals looking to lose weight or maintain a healthy weight. Lower carbohydrate consumption will invoke lower insulin release and thus lower storage of fat and rise in blood sugar levels [49, 50]. However, as the major contributors to hyperglycaemia in type 2 diabetes include a combination of insulin resistance and an inability of pancreatic β-cells to secrete enough insulin [51], it is important to clarify the impact of LCHFD on these important aspects of metabolic regulation.

Studies have shown that insulin-stimulated glucose uptake into muscle and adipose tissue is significantly improved by weight loss on a LCFD diet [52, 53]. LCHFD diet has not necessarily been shown to result in weight reduction in animal studies, regardless of effects on body weight. To the contrary, it has been shown to cause an increased accumulation of lipids in the liver, which negatively affects insulin's ability to reduce hepatic glucose production [54–56]. Thus, from animal studies at least, the proposed benefits versus potential negative effects of an LCHFD on blood glucose control are not very clear. Moreover, whether LCHFDs will prove beneficial for improving glucose control in type 2 diabetes in the longer term will also depend on their impact on glucose-induced insulin secretion.

It is still not very clear that very low carbohydrate intake improves metabolic profile in every diabetes patients, and we need further scientific evidence for this [2, 36]. Although LCHFDs have been shown to reduce post-meal glucose excursions but without any improvement in β-cell function or mass [49, 50, 57], high-dietary fat has been shown, in multiple animal studies, to cause impairments in the ability of insulin to reduce blood glucose resulting in glucose intolerance [58, 59]. Thus, these results from animal studies do not support the recommendation of an LCHFD for use in prediabetes; rather, interventions aimed specifically at reducing obesity and improving insulin sensitivity need to be pursued.
