What happened to the Cambridge diet? The rebrand and its controversial past

December 26, 2025 •

3 min read

In the early 1980s, the original Cambridge diet, developed in the 1960s, quickly gained immense popularity, but this success was overshadowed by tragic deaths and intense regulatory scrutiny in the US market.

Quick Summary

The Cambridge diet was a very low-calorie meal replacement fad that faced serious controversy and led to deaths in the US during the 1980s. The UK version evolved over decades, rebranding most recently to The 1:1 Diet by Cambridge Weight Plan, with changes to its format and calorie levels.

Key Points

Rebranded Name: The Cambridge diet is now officially known as The 1:1 Diet by Cambridge Weight Plan.
1980s US Controversy: The original US program failed due to health concerns, including deaths linked to its extremely low-calorie regimen, which led to FDA scrutiny.
Evolution in the UK: The UK version evolved over time, raising calorie levels and expanding its product line before its final rebrand.
Emphasis on 1:1 Support: The modern diet is built around personalized, one-to-one coaching with a consultant, which is a key differentiator from its past.
Persistent Criticisms: Modern nutritionists still voice concerns about very-low-calorie diets regarding sustainability, potential side effects, and the risk of weight regain.
Medical Consultation is Key: For any very-low-calorie plan, including The 1:1 Diet, medical advice and supervision are recommended.

The Controversial Rise and Fall of the Cambridge Diet

The Cambridge diet, a very-low-calorie meal replacement program, was first developed by research scientist Dr. Alan Howard in the 1960s and commercialized in the UK in 1984. It became popular in the US during the early 1980s, sold through a multi-level marketing system. The original plan was highly restrictive, initially requiring as little as 330 kcal per day, with dieters replacing all meals with shakes and soups. This approach aimed to induce ketosis for rapid weight loss.

The Crisis in the United States

In the mid-1980s, the US version faced a major crisis. Following several deaths potentially linked to the diet's severe restriction, the U.S. Food and Drug Administration (FDA) intensified its scrutiny. Facing pressure, the company raised calorie guidelines to 800 kcal, but lawsuits and public backlash ultimately led to the US operation's bankruptcy. This solidified the Cambridge diet's image as a risky fad in the US.

The UK's Evolving Journey and Strategic Rebrand

While the US brand collapsed, the UK operations continued, undergoing significant changes. The UK company, initially the Cambridge Weight Plan, developed new products beyond shakes and soups. In 2019, it was rebranded as "The 1:1 Diet by Cambridge Weight Plan". This rebrand emphasized personalized, one-to-one support from a consultant, aiming to distance itself from past controversies and highlight its modern approach.

Comparing the Past and Present Cambridge Diet Programs


Feature	Original Cambridge Diet (US, 1980s)	The 1:1 Diet (Modern, UK)
Calorie Intake	Initially as low as 330 kcal/day, later raised to 800 kcal/day under regulatory pressure.	Varies across six flexible "Steps," ranging from 450 to 1,500+ kcal/day.
Product Range	Limited to liquid meal replacements like shakes and soups.	Extensive range including shakes, soups, bars, porridges, and savory meals.
Supervision	Sold through multi-level marketing with little to no professional medical oversight.	Relies on one-to-one support from a trained consultant, with GP approval recommended for younger or at-risk individuals.
Safety & Regulation	Associated with health concerns and deaths, leading to intense FDA scrutiny and collapse of the US brand.	Products are formulated by nutrition experts and supported by modern clinical trials, though VLCDs still carry inherent risks.

Modern Perspectives on the Diet's Evolution

The evolution of the Cambridge diet reflects changing views on weight loss. While very low-calorie diets can yield rapid results, modern science prioritizes sustainable, holistic approaches.

Criticisms and Drawbacks

Despite changes, general criticisms of very-low-calorie diets remain. These include potential issues with:

Sustainability: Restrictive initial phases can make long-term adherence and developing sustainable habits challenging.
Metabolic Slowdown: Severe restriction may slow metabolism, potentially increasing the risk of weight regain (yo-yo effect).
Side Effects: Initial stages can cause fatigue, headaches, dizziness, constipation, or bad breath.
Cost: Proprietary meal replacement products can be expensive.

The Role of The 1:1 Diet Consultant

A significant modern addition is the emphasis on personalized consultant support. This one-on-one coaching provides motivation and accountability, a crucial factor in many weight loss journeys.

What happens on The 1:1 Diet?

The modern program uses a six-step structure to gradually reintroduce regular food. While tailored, the steps generally progress as follows:

Sole Source: Primarily meal replacements (450-600 kcal/day) for up to 12 weeks, along with significant water intake.
Meal and 2 Products: Introduces one lean meal alongside two meal replacements.
Meal and 1 Product: Allows for two healthy meals plus one meal replacement.
Increasing Meal Frequency: Incorporates more conventional meals while still using some products.
Reintroduction to Normal Eating: Focuses on healthy habits with minimal product use.
Maintenance: A long-term plan emphasizing balanced nutrition and ongoing support.

Conclusion: The Final Verdict

The original 1980s Cambridge diet is now The 1:1 Diet, a significantly evolved program. While its history includes controversy and safety concerns from its initial restrictive format, the modern version offers a wider range of products, a structured step plan, and personalized consultant support.

The suitability of The 1:1 Diet depends on individual health and goals. Medical supervision is vital for very-low-calorie diets, and the success of the current plan relies on both the products and the ongoing personal coaching. The Cambridge diet's legacy is a cautionary one that led to a re-engineered approach, though the debate about the long-term effectiveness and safety of VLCDs persists.

For more information on the current program, visit the official website: The 1:1 Diet by Cambridge Weight Plan.

Frequently Asked Questions

The 1:1 Diet is the modern name for the program previously known as the Cambridge Weight Plan and originally as the Cambridge diet. It is a meal replacement diet that uses a step-by-step approach with personalized one-to-one consultant support.

The initial US version of the Cambridge diet from the 1980s was problematic due to its extremely low calorie counts (as low as 330 kcal/day), which were associated with several deaths and prompted investigations by the FDA.

No, the products and program have evolved significantly since the 1980s. The 1:1 Diet offers a much broader range of products and a more structured plan with higher, flexible calorie levels across six different steps.

Similar to the original, the very low-calorie steps of The 1:1 Diet can induce ketosis. However, the program progresses through steps that reintroduce regular food to move beyond this initial phase toward sustainable eating.

Common side effects, particularly during the initial low-calorie stages, can include fatigue, headaches, constipation, dizziness, and bad breath. These often subside as the body adjusts and more food is reintroduced.

Critics suggest that without significant and permanent lifestyle changes, weight regain is a risk with very-low-calorie diets due to metabolic adaptation. The modern 1:1 Diet program includes maintenance phases and consultant support to address this.

Dieters work individually with a dedicated consultant who provides one-on-one coaching, tracks progress, offers motivation, and helps personalize the program. This support is a central element of the modern diet's strategy.