The National Health Service (NHS) in the UK has long been a trusted source of health and medical advice. This article examines the NHS's stance on healthy eating, particularly in relation to low-carbohydrate diets, and how this aligns with current scientific understanding.
Current NHS Dietary Guidelines
The NHS currently recommends basing meals on "higher fiber starchy carbohydrates." This implies including starchy carbohydrates with every main meal. These dietary guidelines, established in the 1980s, advocate a shift from a high-fat, low-carb diet to a low-fat, high-carb diet.
The Evolving Understanding of Diet
However, these guidelines have faced increasing scrutiny. Research published in the British Medical Journal in 2015 suggested that the historic dietary advice on fats "should not have been introduced," citing advancements in research methods and a better understanding of study designs. A 2016 report by the National Obesity Forum also questioned the validity of current dietary guidelines. Furthermore, the launch of the Public Health Collaboration, a charity addressing the problems associated with the NHS's low-fat dietary guidelines, indicates a growing concern about the effectiveness of the current recommendations. Data from Diabetes UK highlight the rising prevalence of diabetes in the UK, suggesting that the current dietary guidelines may be oversimplified and based on outdated advice. The NHS spends a significant portion of its budget (10%) on diabetes annually, indicating the need for a re-evaluation of dietary guidelines based on current research.
Low-Carbohydrate Diets: An Alternative Approach
A low-carbohydrate diet typically involves limiting carbohydrate intake to less than 130g per day and increasing the consumption of high-fat foods. Low-carbohydrate diets, like the ketogenic diet (less than 50g carbohydrates per day), have gained popularity in recent years, although they have been used for centuries to treat certain medical conditions, such as managing type 2 diabetes and treating epilepsy in children when medication is ineffective.
When carbohydrate intake is restricted, the body relies on ketone bodies for energy. Ketosis, or "burning fat," can be achieved in approximately 2-4 days by consuming less than 50g of carbohydrates per day. After this period, the body begins to break down fat for energy. Studies have linked low-carb diets to decreased levels of ghrelin, the hunger hormone, leading to reduced calorie intake and subsequent weight loss.
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How Low-Carb Diets Work
The principle behind a low-carb diet is that restricting carbohydrate intake forces the body to burn fat for fuel. Normally, the body uses glucose from carbohydrates as its primary energy source. When carbohydrate intake is limited, the body turns to stored fat. After about 3-4 days of carbohydrate restriction, the body's carbohydrate reserves are depleted, and it begins to convert stored fat into ketones in the liver, a process called ketosis.
The speed at which ketosis is achieved depends on factors such as BMI, body fat percentage, and resting metabolic rate. To induce ketosis, carbohydrate intake must be significantly restricted, sometimes to as little as 20-50g per day.
What to Eat and Avoid on a Low-Carb Diet
A low-carb diet primarily consists of protein, fat, and non-starchy vegetables. Suitable foods include meat, fish, oils, butter, dairy, and low-carb vegetables like leafy greens, as well as fruits like avocado and olives. When choosing fats and proteins, it's important to limit trans fats and include plenty of non-starchy vegetables to ensure adequate vitamin and mineral intake.
Foods to avoid include bread, pasta, rice, cereals, and most baked goods. Depending on the specific diet, it may also be necessary to restrict legumes, beans, root vegetables, sweetcorn, some fruits, and starchy vegetables like potatoes. It's also important to monitor beverage consumption, limiting fruit juices, fizzy drinks, cordials, and milk-based drinks.
Potential Benefits of Low-Carb Diets
Restricting carbohydrates and increasing protein intake may help suppress appetite hormones and manage hunger. Higher protein intake can also increase the rate at which the body burns calories. Studies suggest that low-carb diets can lead to weight loss, although initial weight loss is primarily water. Some studies have also indicated that ketones may play a role in reducing inflammation in the body.
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Considerations and Potential Drawbacks
While low-carb diets can lead to rapid weight loss in the short term, there is no evidence that they are more effective than standard calorie-restricted diets in the long term (beyond 12 months).
Cutting carbohydrates can be a useful weight-loss strategy, but it can also lead to side effects such as nausea, headaches, fatigue, and electrolyte imbalance, making it difficult to maintain and potentially dangerous. It's also important to remember that much of the initial weight loss is water, which is regained when a more balanced diet is resumed.
Furthermore, low-carb diets can make it difficult to achieve the recommended daily fiber intake (30g per day), which is essential for digestion, gut health, and overall well-being.
WHO Guidelines on Fats and Carbohydrates
The World Health Organization (WHO) has updated its guidance on total fat, saturated and trans-fat, and carbohydrates, based on the latest scientific evidence. The new guidelines aim to reduce the risk of unhealthy weight gain and diet-related noncommunicable diseases like type 2 diabetes, cardiovascular disease, and certain cancers.
Fat Intake Recommendations
The WHO emphasizes that both the quantity and quality of dietary fat are important for good health. Adults should limit total fat intake to 30% of total energy intake or less. Fat consumed should primarily be unsaturated fatty acids, with no more than 10% of total energy intake from saturated fatty acids and no more than 1% from trans-fatty acids from both industrially produced and ruminant animal sources.
Read also: Understanding potatoes and carbohydrate content
Saturated and trans-fatty acids can be replaced with polyunsaturated fatty acids, monounsaturated fatty acids from plant sources, or carbohydrates from foods containing naturally occurring dietary fiber, such as whole grains, vegetables, fruits, and pulses. Saturated fatty acids are found in fatty meat, dairy foods, and hard fats and oils like butter, ghee, lard, palm oil, and coconut oil. Trans-fatty acids are found in baked and fried foods, pre-packaged snacks, and meat and dairy foods from ruminant animals.
Carbohydrate Intake Recommendations
The WHO's guidance on carbohydrate intake highlights the importance of carbohydrate quality for good health. Carbohydrate intake should primarily come from whole grains, vegetables, fruits, and pulses. Adults should consume at least 400 grams of vegetables and fruits and 25 grams of naturally occurring dietary fiber per day.
The Low Carb Program: A Digital Intervention
The Low Carb Program, developed in 2015 in collaboration with Dr. Unwin, provides structured education, resources, live meet-ups and classes, 1-1 health coaching, and other features to support positive behavior change. A study evaluating the real-world outcomes of patients recruited to the Low Carb Program at an NHS general practice in Southport, United Kingdom, showed that a digital app supporting a transition to a low-carbohydrate diet can be effective in improving glycemic control and enabling weight loss.
Study Results
The study included 45 participants with type 2 diabetes or prediabetes. All participants activated their accounts, and 82% reported outcomes at 12 months. All participants completed at least 40% of the lessons, and 71% completed more than nine of the 12 core lessons. The mean HbA1c decreased from 58.8 mmol/mol at baseline to 54.0 mmol/mol, representing a mean reduction of 4.78 mmol/mol. Participants also showed a statistically significant mean reduction in weight.
Key Elements of the Low Carb Program
The Low Carb Program is a digitally delivered, structured health intervention for adults with type 2 diabetes, prediabetes, and obesity. User data are used to personalize the experience. Participants are given access to therapeutic nutrition education modules tailored to their health status, age, ethnicity, and dietary preferences. The modules are designed to help participants gradually reduce their total carbohydrate intake to less than 130 grams per day, focusing on the reduction of processed and ultraprocessed foods as well as foods high in sugar and refined carbohydrates. The program encourages participants to replace starchy foods with green leafy vegetables, healthy fats, and some protein, emphasizing minimally processed foods, home cooking, and food preparation. The program also stresses the importance of regular contact with health care providers for medication adjustments and provides behavior change resources, including information sheets, meal plans, a recipe library, and suggested food substitution ideas. Users are matched with a digital buddy and given access to a peer-support forum. The platform also includes digital tools for self-monitoring data, such as blood glucose levels, blood pressure, mood, sleep, food intake, and body weight.
Considerations for Specific Populations
Diabetes UK recommends low-carb diets as an effective short-term option for adults with type 2 diabetes who are overweight, as they can help with weight loss and glucose management, as well as reducing the risk of cardiovascular disease. However, they do not recommend such diets for those with type 1 diabetes due to a lack of evidence and state that there is no consistent evidence that a low-carb diet is any more effective than other approaches in the long term.
It should be noted that there have been reports of adverse effects of low-carb diets when adopted by children with diabetes, including poor growth, a greater risk of cardiovascular disease, and psychological problems.
Who Should Avoid Low-Carb Diets?
All diabetics and anyone with a blood sugar management issue should discuss the potential implications of a low-carb diet with their GP and healthcare team before starting such a regime. The same applies to anyone who:
- Is under 18 years old or elderly
- Has a low BMI
- Has a pre-existing medical condition
- Is pregnant or breast-feeding
- Has an emotional or psychological issue around food, including having or being in recovery from an eating disorder, or being on prescribed medication
If your goal is weight loss and you have a lot of weight to lose, you should seek the advice and guidance of a dietitian to ensure that the diet you follow provides all the necessary nutrients you need, including adequate fiber.
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