The 8 Week Blood Sugar Diet is a programme designed to help manage blood sugar levels, reverse type 2 diabetes, and promote weight loss through a low-carb, Mediterranean-style diet.

Created by Dr. Michael Mosley, the plan offers three approaches:

• BSD Fast 800: 800 calories daily for quick results.
• BSD 5:2: 800 calories on two days per week for gradual progress.
• BSD Med Style Low Carb: A flexible, long-term Mediterranean diet.

Key features include calorie limits, nutrient-rich foods like vegetables, olive oil, and nuts, and a focus on reducing liver and pancreas fat. Backed by research, participants have seen significant improvements in blood sugar levels, weight loss, and overall metabolic health.

This diet is ideal for individuals with type 2 diabetes, prediabetes, or those seeking better weight management. However, medical supervision is recommended for very low-calorie plans.

For tracking progress, tools like Continuous Glucose Monitors (CGMs) can provide real-time insights into blood sugar patterns.

Blood sugar science basics

Understanding the role of insulin and how blood sugar is regulated helps lay the foundation for why the 8 Week Blood Sugar Diet works.

Blood sugar and insulin explained

Your body works hard to keep blood sugar levels steady, and two hormones play a major role in this process:

When things go wrong – like with insulin resistance – cells stop responding well to insulin. This means glucose isn’t absorbed effectively, causing blood sugar levels to rise.

Research behind the diet

A study on a strict 600-calorie daily diet over eight weeks showed dramatic results:

• Liver fat dropped by 70% (from 12.6% to 2.9%)
• Fasting glucose returned to normal in just one week
• Participants lost 15% of their body weight
• Plasma triacylglycerol levels were reduced by half

Another clinical trial, lasting two years and involving 262 participants, demonstrated the effectiveness of a low-carb diet.

• 53.5% of participants reversed their diabetes
• 17.6% achieved complete remission
• Participants maintained an average weight loss of 10%

Quick weight loss effects

Losing weight quickly can make a big difference for blood sugar control, but it comes with some challenges. Research highlights a few key points:

• Rapid weight loss may lower calorie burning by 23% and often starts with water and glycogen loss.
• About 25% of people on very low-calorie diets (800 calories or less) may develop gallstones
• Losing more than 5% of body weight over 6-12 months should be monitored closely.

A Mediterranean-style diet is often recommended for its ability to support both quick weight loss and long-term metabolic health.

Next, we’ll break down the diet’s structure and rules.

Diet structure and rules

Learn how the 8 Week Blood Sugar Diet is structured, including its calorie targets, food guidelines, and flexible plan options to suit different lifestyles.

800 calories per day plan

The 8 Week Blood Sugar Diet is built around an 800-calorie daily plan aimed at quick weight loss and better blood sugar management. This phase, lasting anywhere from two to twelve weeks, combines intermittent fasting with Mediterranean-inspired eating habits. The goal? To reduce fat around key organs like the liver and pancreas, helping to improve blood sugar levels.

Here are the main guidelines for the 800-calorie phase:

• Drink 2–3 liters (64–96 fl oz) of calorie-free liquids daily
• Limit meal replacement shakes to a maximum of 2 per day or 10 per week
• Prioritise whole, natural foods instead of processed options
• Stick to a moderately low-carb approach

The diet also provides a clear list of foods to include and avoid during this phase.

Looking to cut back on carbs while supporting your blood sugar goals? Check out our list of 20 quick ways to lower your carb intake for better metabolic health.

Allowed and restricted foods

The focus is on nutrient-packed, whole foods commonly found in a Mediterranean diet. Here's a quick breakdown of what’s recommended:

Daily meal examples

The book offers meal plans that stick to the 800-calorie limit while ensuring balanced nutrition. Here’s an example of a typical day.

• Breakfast (170 calories): Yogurt with passion fruit and almonds
• Lunch (200 calories): Homemade beetroot, apple, and cannellini bean soup
• Dinner (470 calories): Luxury fish pie with celeriac topping

Many participants use calorie-tracking apps like MyFitnessPal or FatSecret to stay on target. The diet also encourages using the plate method: fill half your plate with non-starchy vegetables, one quarter with lean protein, and one quarter with whole grains.

Results and safety factors

This section highlights the outcomes you can expect from the diet and the precautions to keep in mind. It breaks down the diet's effectiveness and provides key safety guidelines.

Blood sugar and weight outcomes

The 8 Week Blood Sugar Diet has shown promising results. Participants often lose 3–5 pounds per week, particularly those with a BMI over 30. One reviewer shared their experience of completing two 8-week cycles, achieving a 60-pound weight loss, normalising blood pressure, and reducing their reliance on medications.

Medical conditions and adjustments

The programme offers several approaches to suit different health needs:

People with prediabetes or type 2 diabetes should consult their healthcare provider to tailor the plan to their specific needs.

Health risks and warnings

Very low-calorie diets (VLCDs), like the 800-calorie plan, require strict medical supervision to ensure safety.

This diet is not recommended if you are:

• Pregnant or breastfeeding
• Under 18 years old
• Over 50 without medical guidance
• Have a BMI below 27
• Have a BMI between 27 and 30 without related health concerns

Potential side effects include fatigue, constipation, nausea, diarrhoea, and an increased risk of gallstones.

Next, we’ll look at actionable steps to start and stick with the programme.

Starting and maintaining the diet

Getting started is one thing—sticking with it is another. Here’s how to begin the 8 Week Blood Sugar Diet and stay on track for long-term success.

First steps

Kick things off with a low-carb Mediterranean-style diet that aligns with specific calorie goals. Before diving in, consult with your healthcare provider to ensure it's the right fit for you.

• Set realistic goals: Aim to lose 5–10% of your body weight. For example, if you weigh 200 pounds, that's about 10–20 pounds.‍
• Pick your plan: Choose the approach that matches your lifestyle and goals – whether you're aiming for rapid results, steady progress, or maintaining long-term habits.

Once you've chosen your plan, think ahead to tackle any challenges you might face.

Problem-solving tips

Dealing with hunger: During the first week, hunger may be a challenge. However, as insulin levels drop and insulin resistance improves, hunger tends to decrease.

Tackling Sleep and Cravings: Aim for 7–8 hours of sleep each night. This helps curb sugar cravings and supports overall health.

Navigating social events:

• Opt for Mediterranean-style dishes.
• Check menus in advance to plan your choices.
• Stick to vegetables, lean proteins, and healthy fats.
• Avoid bread and desserts to stay on track.

Start thinking about how to maintain these habits after the programme ends.

Looking to explore more sustainable ways to manage prediabetes? Check out our guide on the best diets for prediabetes in Australia for expert insights and practical tips.

After 8 weeks

Once you've completed 8 weeks, shift to practices that you can sustain over the long term:

• Stick with Mediterranean-style eating.
• Keep monitoring your blood sugar levels.
• Stay active with regular physical exercise.
• Use intermittent fasting as a flexible way to maintain progress
• Limit alcohol intake and avoid tobacco.

These habits can help you maintain better blood sugar control well beyond the initial phase.

Blood sugar tracking tools

Wearable Continuous Glucose Monitors (CGMs) allow you to track your blood sugar levels in real time, giving you immediate insights into how food and activity affect your glucose. These devices are a great fit for anyone following the 8 Week Blood Sugar Diet, as they align perfectly with its focus on managing blood sugar levels effectively.

How CGMs work

CGMs offer a range of benefits for those looking to improve their diet and overall health. These devices measure your glucose levels every few minutes and send the data straight to your smartphone, making it easy to stay informed. Research highlights their effectiveness:

• 87% of users make healthier food choices based on the feedback
• 70% of overweight or obese users see weight loss
• Users lose an average of over 10 pounds

Here are some popular CGM options to consider:

For those looking for more tailored support, there are programmes that take CGM tracking to the next level.

Vively CGM Program

Vively combines CGM technology with personalised guidance from Australian dietitians, making it a great match for the 8 Week Blood Sugar Diet. The program includes:

• Real-time glucose tracking with actionable insights
• Integration with fitness devices like Apple Watch, Fitbit, and Oura
• One-on-one nutrition coaching, delivering results 1.6x better than standard plans
• Data syncing for sleep, nutrition, and activity tracking

Pricing for the program is flexible:

• CGM Plan: £169 (includes 1 CGM sensor)
• App Only Plan: £39/month (use your own sensor)‍
• Additional sensors: £79 each

With a CGM, you can monitor how meals affect your glucose, see how quickly your levels return to normal, test the impact of healthy fats on spikes, and observe how stress or sleep patterns influence your readings.

Wrapping it up

This diet focuses on managing blood sugar through a low-carb Mediterranean-style approach. It offers three different plans:

The primary goal is reducing fat around critical organs like the liver and pancreas. Once these guidelines are in place, the next focus is creating lasting habits.

Next steps

To maintain progress, consider these practical steps:

• Set a "trigger weight" to know when to return to the 800-calorie plan.
• Use tools like CGM devices or regular testing to track blood sugar levels.
• Keep a detailed log of your daily carbohydrate intake.
• Incorporate consistent physical activity into your routine.

Sticking to these steps can help sustain improvements in metabolic health.

For additional support, check out these resources:

• The Fast 800 Online Programme: Offers structured guidance and community support.‍
• The Metabolic Health Guide by Dr Michelle Woolhouse, Integrative GP and Vively’s medical founding director, and Charlotte Battle, Vively’s lead dietitian