The Protein Power diet, championed by Drs. Michael and Mary Eades, advocates a high-protein, low-carbohydrate approach to eating. The Protein Power diet is presented not merely as a weight loss strategy, but as a comprehensive lifestyle plan aimed at improving overall health, resetting metabolism, and preventing diseases. Published initially in 1996, the core philosophy of the Protein Power diet has remained relevant in discussions about ketogenic and similar dietary approaches.
Core Principles of Protein Power
The Protein Power diet operates on several key principles that distinguish it from conventional dietary advice.
Prioritizing Protein
At the heart of the Protein Power approach is the emphasis on protein consumption. The Protein Power diet emphasizes that a diet rich in protein helps maintain muscle mass, boosts metabolism, and promotes satiety, making it easier to lose weight compared to high-carb diets. Protein is positioned as the cornerstone of a balanced, effective nutritional strategy. The book provides tools to calculate personal protein needs based on body size and activity level. The Protein Power diet recommends consuming a 90-120 g or 3-4 oz serve of protein with at least 2 meals daily, depending on your weight/size.
Carbohydrate Restriction
A cornerstone of the Protein Power diet is the restriction of carbohydrate intake. The Eades argue that reducing carbohydrate intake, particularly refined carbs and sugars, helps regulate insulin levels, reduce fat storage, and prevent or manage conditions like diabetes, obesity, and heart disease. This low-carb approach is a key pillar of the "Protein Power" plan. The Protein Power diet involves a phased approach to carb intake (intervention, transition, and maintenance phases). Phase 1 of the diet recommends that you eat less than 30 grams (net) of carbohydrate a day. Phase 2 of the diet allows up to 55 g of carbohydrates daily. The Maintenance Phase allows 60 - 150 carbs a day, depending on what works best for you and your body.
Embracing Dietary Fat
Challenging the low-fat diet trends prevalent at the time of its publication, the Protein Power diet defends dietary fat as a necessary and healthy energy source when carbs are limited. It aligns with the idea that fats, especially from natural sources, support overall well-being when paired with protein.
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Individualized Nutrition
Recognizing that one size does not fit all, the Protein Power diet advocates for tailoring the eating plan to individual needs. The authors provide tools to calculate personal protein needs based on body size and activity level, as well as a phased approach to carb intake (intervention, transition, and maintenance phases). This customization aims to optimize results for each person’s unique physiology.
Lifestyle Integration
Beyond diet, the book stresses the importance of combining the high-protein, low-carb eating plan with exercise and other healthy habits to maximize fat loss, energy levels, and long-term health outcomes.
A Deeper Dive into the Science
The Protein Power diet's effectiveness is rooted in its impact on various physiological processes. High-protein diets (HPDs) have been shown in clinical trials to reduce body weight and enhance body composition by decreasing fat mass while preserving fat-free mass (FFM) in both low-calorie and standard-calorie diets. Fairly long-term clinical trials of 6-12 months reported that a high-protein diet (HPD) provides weight-loss effects and can prevent weight regain after weight loss.
The Role of Hormones
HPDs influence gut-derived hormones that regulate appetite. Glucagon-like peptide-1, cholecystokinin, and peptide tyrosine-tyrosine reduce appetite, while ghrelin enhances appetite. HPD increases these anorexigenic hormone levels while decreasing orexigenic hormone levels, resulting in increased satiety signaling and, eventually, reduced food intake.
Energy Expenditure and Diet-Induced Thermogenesis (DIT)
HPDs increase energy expenditure through two primary mechanisms. First, proteins have a markedly higher DIT than carbohydrates and fats. Second, protein intake prevents a decrease in FFM, which helps maintain resting energy expenditure despite weight loss.
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Clinical Evidence
Meta-analyses of randomized controlled trials (RCTs) have consistently demonstrated the benefits of HPDs. Compared with subjects in the SPD group, those in the HPD group showed a significant reduction in BW, fat mass, and blood triglycerides and a significant increase in FFM and resting energy expenditure (REE). Studies involving ad libitum diets have also shown that participants in the high-protein group significantly lost BW and fat mass compared with those in the high-carbohydrate diet group.
Long-Term Weight Management
HPDs have been shown to aid in preventing weight regain after weight loss. Participants in the protein group showed 50% less weight regain compared with control-group participants.
Addressing Concerns and Misconceptions
Despite its benefits, the Protein Power diet has faced scrutiny regarding its potential impact on bone health and renal function.
Bone Health
Contrary to the hypothesis that HPDs increase bone resorption, a meta-analysis of RCTs observed that subjects in the HPD group were not significantly different from low-protein-diet subjects with regard to bone mineral density of the lumbar spine and hips. Low protein intake is generally considered a nutritional deficiency and has been described as a factor affecting osteoporosis development in older adults.
Renal Function
While there have been concerns that HPDs may deteriorate renal function, studies have found no declining renal function in obese adults with normal renal function over two years. Overall, HPD does not lead to reduced bone mineral density. On the contrary, high protein intake can help prevent bone loss in older adults who are prone to nutritional deficiency. While HPD also does not affect renal function in healthy people, it can adversely affect renal function in people with kidney disease.
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Mechanisms Underlying HPD-Induced Weight Loss
The Protein Power diet's effectiveness hinges on its ability to increase satiety and energy expenditure.
Increased Satiety
Increased satiety from protein intake is associated with elevation of blood amino acid (AA) concentration, hunger-inhibiting hormones, diet-induced thermogenesis (DIT), and ketone body levels. Dietary protein elevates GLP-1, CCK, and PYY levels, which are secreted in the gut and diminish appetite while also decreasing ghrelin levels, which increases appetite.
Increased Energy Expenditure
Protein is known to increase energy expenditure by having a markedly higher DIT than carbohydrates and fat, and increasing protein intake preserves REE by preventing FFM decrease.
Criticisms and Considerations
Despite its merits, the Protein Power diet is not without its critics. Some reviewers have noted that the book includes recommendations for unhealthy and junky foods, which may be off-putting to some readers. Others have pointed out that the book lacks step-by-step processes and may be difficult to follow due to its system of assigning weight to carbs in food.