Obesity has become a global pandemic, with 2.8 million people dying each year as a result of being overweight or obese, according to the World Health Organization (WHO).
Within the framework of strategies to combat obesity, we find different dietary and physical activity proposals. Among very low‑calorie diets (VLCDs) , we find the protein diet, a type of ketogenic diet (KD) with minimal fat intake, in accordance with the guidelines of the Scientific Review and Cooperation Group of Member States on Food‑Related Issues (SCOOP) for the application of a very low‑calorie diet.
The objective of this scientific review is to compile the scientific evidence that assesses the effectiveness, safety, and long‑term maintenance of the effects of VLCDs, and specifically the protein diet, applied within a multidisciplinary approach such as the PronoKal® method, on overweight and obesity and its relationship with physical exercise.
What Does a “High Protein Liquid Diet” Mean?
A high-protein liquid diet is a very low‑calorie ketogenic diet with minimal fat intake, as recommended by the SCOOP group for very low‑calorie diets. Protein intake is adjusted to 0.8–1.2 grams of protein per kilogram of ideal body weight and is obtained through food products containing high‑biological‑value proteins.
Carbohydrate intake is less than 50 g/day. Additionally, the high protein liquid diet is supplemented with vitamins, minerals, and omega fatty acids to meet the recommended daily amounts for following a very low‑calorie diet (VLCD).
It was in 1921 that Dr. Wilder of the Mayo Clinic coined the term “ketogenic diet,” referring to a dietary intervention aimed at inducing ketosis (the formation of ketone bodies) similar to that of fasting.
This dietary approach has been widely used to treat drug‑resistant epilepsy. Since then, different variations of the ketogenic diet have emerged, one of the most popular being Dr. Atkins’s diet, published in 1998 in his book.
The difference between the protein diet and Dr. Atkins’s diet is that the latter reduces carbohydrate intake to a greater or lesser extent, but increases the proportion of protein, and sometimes fat as well, above normal daily requirements.
35+ High-Protein Liquid Diet Recipes
Here is a numbered list of 35+ recipe names (only names) suitable for a high protein liquid diet (very low calorie, high protein, low carbohydrate, liquid or semi‑liquid consistency – such as shakes, soups, puddings, and broths). These are designed to mimic VLCD products or homemade alternatives.
- Classic Vanilla Protein Shake (Whey Isolate + Water)
- Chocolate Peanut Butter Protein Smoothie (Unsweetened Almond Milk)
- Strawberry and Whey Protein Frappé (Ice, Water, No Sugar)
- Creamy Chicken Bone Broth Protein Soup
- Egg White Protein Shake (Pasteurized Egg Whites + Cocoa)
- Iced Coffee Protein Latte (Whey + Cold Brew, No Sugar)
- Unflavored Collagen Peptides with Warm Water
- Beef Broth Protein Boost (Collagen + Beef Bouillon)
- Matcha Green Tea Protein Shake (Plant Protein + Unsweetened Matcha)
- Coconut Cream Protein Pudding (Protein Powder + Coconut Milk, Chilled)
- Savory Tomato and Whey Soup (Tomato Puree + Unflavored Protein)
- Cinnamon Roll Protein Shake (Whey + Cinnamon + Stevia)
- Lemon Meringue Protein Water (Lemon Juice + Clear Whey Isolate)
- Creamy Mushroom and Chicken Protein Soup (Blended)
- Vanilla Chia Seed Protein Pudding (No Carb, Chia + Protein)
- Salted Caramel Protein Shake (Salted Caramel Whey + Water)
- Frozen Blueberry Protein Smoothie Bowl (Thick, Eaten with Spoon)
- Warm Turmeric and Ginger Protein Broth (Unflavored Protein)
- Peppermint Mocha Protein Shake (Whey + Cocoa + Peppermint Extract)
- Egg Drop Soup with Unflavored Whey (Whisked into Hot Broth)
- Peanut Butter Cup Protein Shake (Peanut Butter Powder + Chocolate Whey)
- Clear Protein Electrolyte Drink (Lemon Lime, No Sugar)
- Vanilla Masala Chai Protein Latte (Whey + Spices + Tea)
- Cream of Broccoli Protein Soup (Blended Broccoli + Unflavored Protein)
- Banana Cream Protein Pudding (Banana Extract + Casein Pudding)
- Smoked Paprika Chicken Protein Soup (Bone Broth + Whey)
- Coconut Matcha Protein Smoothie (Vegan Protein + Coconut Milk)
- White Chocolate Raspberry Protein Shake (Clear Whey)
- Savory Pumpkin and Sage Protein Soup (Canned Pumpkin + Unflavored Protein)
- Maple Pecan Protein Shake (Maple Extract + Pecan Flavoring)
- Creamy Tomato Basil Protein Soup (Tomato + Whey + Basil)
- Pineapple Coconut Protein Water (Clear Whey + Coconut Water)
- Chocolate Hazelnut Protein Spread (Mixed with Water to a Pudding)
- Warm Vanilla Protein Porridge (Protein Powder + Hot Water + Thickener)
- Lemon Chiffon Protein Mousse (Whipped Egg Whites + Whey + Lemon)
- Roasted Red Pepper and Turkey Protein Soup (Blended)
- Espresso Protein Shot (Double Espresso + Unflavored Collagen)
- Mint Chocolate Chip Protein Shake (Whey + Mint Extract + Cocoa Nibs ground)
More About High-Protein Diets
Multiple studies have been conducted comparing the weight loss effects of different types of isocaloric diets with varying macronutrient ratios.
Short‑term studies (3 to 6 months) have shown greater weight loss with low‑carbohydrate, high‑protein diets compared to conventional hypocaloric diets, which are higher in carbohydrates and lower in fat.
However, medium‑term studies (1 to 2 years) have not shown significant differences in weight loss between isocaloric diets with different macronutrient ratios.
Carbohydrate‑restricted diets appear to provide moderate benefits on cardiovascular risk factors, as they increase HDL cholesterol levels and, in the short term, reduce triglycerides, glucose, and fasting insulin.
On the other hand, diets low in saturated and omega‑6 polyunsaturated fats, but moderate in omega‑3 polyunsaturated fats, are correlated with a lower incidence of cardiovascular disease and breast cancer.
One of the most worrying aspects related to obesity is the high dropout rate and weight regain associated with existing weight‑loss treatments.
Conclusion
Obesity is currently one of the main public health problems worldwide, due to its high prevalence and increasing trend. Globally, the incidence of obesity has doubled since 1980.
According to the World Health Organization, in 2008, more than 1.4 billion adults worldwide were overweight, and of these, more than 500 million were obese. Each year, 2.8 million people die as a result of being overweight or obese.
In Spain, according to data from the ENRICA study, 62% of the population is overweight; specifically, 39% are overweight (body mass index or BMI ≥ 25‑29.9 kg/m²) and 23% are obese (BMI ≥ 30 kg/m²).
The prevalence of obesity increases with age and is higher in men than in women (except for those aged 65 and over). Furthermore, the study indicates that more than a third of men with obesity report having received medical advice to lose weight but not following it.
Obesity, and to a lesser extent overweight, is a risk factor for cardiovascular disease, type 2 diabetes mellitus, hypertension, and hypercholesterolemia. Addressing excess weight is therefore a primary objective of strategic planning within the framework of public health.