**12. Summary**

From the current evidence and above reviews of lower carbohydrate diets, it can be postulated that LCHF diets reduce insulin resistance, improves glycaemic regulation and has positive effects on reducing cardiovascular risk factors, including reducing serum triglyceride, increasing HDL cholesterol, increasing LDL particle size and reducing blood pressure. A substantial proportion of individuals have also been shown to discontinue one or more diabetes medication.

Low-carbohydrate high-fat (LCHF) diet has been shown to be as effective as other diets for weight reduction, through increased satiety and reduction in calorie intake. LCHF diet also helps improve glycaemic control in type 2 diabetes mellitus and in otherwise healthy patients with insulin resistance.

Some of the benefits of the LCHF diet results from the often large weight loss typically produced by this diet. Therefore, at least some of the beneficial changes from LCHF diet would also be experienced by patients prepared to adhere to any calorie-restricted diet. LCHF diets control energy balance through increased satiety and reduced ad libitum energy intake while encouraging the ingestion of a nutrient-dense diet by replacing refined foods with natural foods.

LCHF diets have beneficial effects on cardiovascular risk factors through their effect on blood lipid concentrations. They decrease triglycerides, apoprotein B and saturated fat levels in blood, together with reduction in small dense LDL particles and increase in HDL-C concentrations. Their effect on LDL-C concentration seems to be variable.

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LCHF diet, thus far, has proven to be a safe and efficacious strategy for weight loss and improved health outcomes especially for those with metabolic syndrome and NAFLD. Thus, LCHF diets may be the ideal choice for patients who have struggled to lose weight on traditional diets, especially T2DM with or without cardiovascular risk factors. A life-long completely carbohydrate-free diet is unlikely to be achievable but a LCHF, through reducing post-meal glucose excursions, could potentially have some benefit for improving glucose control in diabetes. However, from animal models, it has been shown that there are no longer term benefits for β-cell function or glucose metabolism.

Notably, most diets are effective at inducing at least short-term weight loss, usually followed by some weight regain as adherence diminishes. However, it can be argued that LCHF diets perform at least as well as do any other dietary approaches. In practice, beneficial responses to any diet is entirely dependent on the degree of patients' adherence, so a LCHF diet is only likely to benefit patients motivated to comply.

A growing understanding that obesity/hypertension/T2DM/non-alcoholic fatty liver disease/ atherogenic dyslipidaemia and metabolic syndrome may all be substantially influenced by a high-carbohydrate diet, acting on a single metabolic state, insulin resistance—could revolutionise the dietary management of these conditions over the next few years. It can therefore be argued that the LCHF eating plan should form an integral part of medical management for all these conditions.

LCHF diet may not be an answer for everyone as every individual metabolic profile is different. However, it may present a sensible dietary option for weight loss and health improvement in certain group of patients. Despite its numerous benefits, individual LDL-C responses need to be monitored and continued emphasis should be placed on nutrient-rich choices, avoiding ultra-processed foods. We need more well-designed comparative studies to confirm whether the metabolic changes from LCHF diet will be sustained long term.
