Question

A weightreducing diet heavily promoted some years ago required the daily intake of a "liquid protein" soup made of hydrolyzed gelatin (derived from collagen), water, and an assortment of vitamins. All other food and drink were to be avoided. People on this diet typically lost 10 to \(14 \mathrm{lb}\) in the first week. a. Opponents argued that the weight loss was almost entirely due to water loss and would be regained very soon after a normal diet was resumed. What is the biochemical basis for this argument? b. A few people on this diet died. What are some of the dangers inherent in the diet, and how can they lead to death?

Short answer

The initial weight loss is water loss due to glycogen depletion. The diet risks include nutrient deficiencies and potential cardiac issues leading to death.

Step-by-step solution

Understanding Glycogen and Water Storage

The body stores carbohydrates in the form of glycogen, primarily in the liver and muscles. Each gram of glycogen is stored with about 3-4 grams of water. When people start a low-calorie diet with limited carbohydrates, such as the one described, glycogen reserves are depleted quickly, leading to a substantial loss of water weight.

Identifying the Reason for Rapid Weight Loss

When the 'liquid protein' soup diet is followed, the significant reduction in carbohydrate intake causes a depletion of glycogen. Since glycogen is stored with water, its depletion results in a quick loss of water weight, which explains why individuals on this diet experience a rapid weight loss in the first week.

Analyzing the Temporary Nature of Weight Loss

Once the diet is stopped and normal carbohydrate intake is resumed, the body replenishes its glycogen stores, along with the water that accompanies it. This often leads to regaining the weight that was primarily water loss, which supports the argument that the initial weight loss was temporary.

Identifying Danger: Nutrient Deficiency

The diet primarily relies on liquid protein and lacks other essential nutrients like fats, carbohydrates, and vital micronutrients. This deficiency can lead to severe health problems, such as muscle wasting and impairment of organ function due to lack of energy and essential nutrients needed for metabolic processes.

Examining Risk of Cardiac Issues

Severe calorie and nutrient restrictions, as seen in this diet, can lead to electrolyte imbalances, especially affecting potassium levels. Low potassium and other electrolyte imbalances can lead to arrhythmias (irregular heartbeats) and sudden cardiac issues, which can be fatal.

Considering Protein Induced Metabolic Stress

Excessive protein intake without balanced nutrients can lead to an increased burden on the kidneys and liver as they work to metabolize protein and excrete nitrogen waste. In some cases, this strain can result in organ malfunction or failure, contributing to the risk of death.

Key concepts

Glycogen and Water Storage

When starting a diet that reduces carbohydrate intake drastically, you might notice an initial rapid weight loss. But what's fundamentally happening here? The body stores carbohydrates as glycogen in the liver and muscles.
Each gram of glycogen is accompanied by 3 to 4 grams of water. This means that as glycogen levels decrease, so does the stored water. Such diets deplete glycogen quickly, resulting in substantial water loss during the first few days. This is why people on low-carb diets like the 'liquid protein' plan observe quick weight reduction initially.
Once regular eating resumes, the body begins to restore its glycogen levels, bringing the water back in as well. This rehydration essentially reverses the initial weight loss, clarifying why many people regain the weight shortly after ending such diets. While glycogen and water storage might give a short-term weight loss effect, it’s important to realize it’s mostly not fat loss, and hence, not permanent.

Nutrient Deficiency

A balanced diet is fundamental for overall health, and a diet lacking in essential nutrients has significant dangers. The 'liquid protein' diet primarily consists of hydrolyzed gelatin and water, with selected vitamins.
Although it provides some proteins, it dismisses other crucial components like fats, carbohydrates, and numerous essential micronutrients. These missing nutrients are vital for maintaining energy, supporting cellular functions, and performing metabolic activities. Lacking these nutrients can lead to muscle wasting as the body taps into muscle protein for energy. Crucially, it can impact organ function, as organs need a range of nutrients to perform their tasks efficiently. A nutrient-deficient diet can also weaken the immune system, leaving the body prone to infections and diseases. It's a reminder of the importance of a diet that covers all the macronutrient bases along with necessary vitamins and minerals.

Electrolyte Imbalance

Electrolytes play a crucial role in maintaining heart, muscle, and nerve functions. These include substances like potassium, sodium, calcium, and magnesium that help regulate various bodily systems.
The severe calorie and nutrient restrictions inherent in the 'liquid protein' diet can dangerously disturb electrolyte balance, particularly affecting potassium. Insufficient potassium levels can trigger heart arrhythmias or irregular heartbeats. Such imbalances can lead to devastating cardiac problems, sometimes resulting in sudden cardiac arrest. Keeping electrolyte levels stable is critical, and this is often disrupted by diets that neglect potassium and other electrolytes.
Thus, in attempting weight loss or dietary changes, it is vital to ensure the plan doesn’t compromise these life-supporting substances.

Protein Metabolism Stress

While protein is an important part of the diet, excessive reliance on it, without proper balance, can stress metabolic processes. Proteins are metabolized in the liver and kidneys, where protein breakdown results in nitrogen waste.
High protein consumption on diets such as the 'liquid protein' plan can increase pressures on these organs. This might lead to potential malfunction or failure over prolonged periods if the body cannot adequately meet the nutrient requirements. Moreover, the body needs carbohydrates and fats for energy, and in their absence, it will resort to metabolizing protein excessively, which is not its preferred energy source. This can enhance stress on organ systems and may result in detrimental health effects over time.
Thus, while formulating diet plans, it’s critical to strike the right nutrient balance where every class of nutrients plays its dedicated role without overwhelming any segment of body functions.