Research shows weight loss and key nutrients play important roles in disease risk prevention. In this critical review, we highlight the importance of looking closely at the details of a study.
Overview
What did they test? Researchers tested how two diets with different key nutrients can impact weight loss and various biomarkers important for cardiometabolic health.
What did they find? A high-nutrient quality diet improved various disease risk factors and reduced body weight more than a low-nutrient quality diet. However, complications in the design may have led to misleading conclusions.
What does it mean for you? Diets rich in whole foods provide more nutrients that can improve various chronic disease risk factors. However, weight loss independent of diet quality can also improve disease risk factors.
What’s the Problem?
Obesity spans beyond a lack of work ethic or discipline; it’s a multi-factorial problem. Differences in genetics, environments, socioeconomic status, and the increased added calories in foods are among many factors contributing to the problem. It’s well known most Americans are overweight and obese, which increases the risk for certain diseases 2. With the COVID-19 crisis becoming a part of global society, obese individuals face new grim realities. Evidence indicates obesity results in more severe COVID-19 illnesses and death 6. Therefore, some individuals should prioritize a “healthy” body weight to reduce disease and illness risks. The word ‘healthy’ can be ambiguous, with various definitions and ways to measure it depending on the context. Determining someone’s overall health requires assessments beyond physical characteristics. However, the unfortunate reality is that in addition to the increased risk of COVID-19, excessive body weight has been shown to lead to other cardiometabolic (cardiovascular system and metabolism) diseases such as diabetes, hypertension, and insulin resistance, heart failure, and others 7. Because of the direct relationship between calorie intake and body weight, various diets and lifestyle modifications have been the focus to combat overweight and obesity. Evidence suggests that weight loss as little as 5% of initial body weight has been shown to improve some of these cardiometabolic risk factors, with even greater weight loss further improving various risk factors 8 9. It’s important to understand the distinction between the fat we store in our bodies and the dietary fats we eat. We store fat into two primary types, subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT). The fat around your internal organs is what constitutes VAT and higher levels have been shown to be associated with more cardiometabolic disease risk factors 10.
Aside from fat tissue, specific biomarkers can also be helpful in evaluating disease risk factors. Like body fat, dietary fat can be categorized into two primary types, saturated and unsaturated. We won’t get too deep here, but the saturation refers to the chemical structure of fatty acids and the number and location of double carbon bonds. Saturated fats are the ones you typically find in animal products like beef, dairy, butter. On the other hand, unsaturated fats are largely plant-based like avocado, nuts, vegetable oils, etc. Unsaturated fatty acids with one double bond in its carbon chain are known as monounsaturated fatty acids (MUFAs). Unsaturated fatty acids with more than one double bond are referred to as polyunsaturated fatty acids (PUFAs). There’s human data demonstrating people live longer and reduce CVD when replacing PUFAs with saturated or trans-fats 3 4. However, data is messy and should be evaluated cautious and critically 11. There is also some data showing positive benefits for cardiovascular disease (CVD) risk factors by swapping animal-based MUFAs for plant-based MUFAs 12. This is only one study, but together this data brings up a valid argument for swapping out some animal-based food sources for plant-based food sources to reduce body fat but also maximize health improvements through various biomarkers. Let’s take a close, cynical look at the current study that researched this exact question!
Purpose
This study compared two diets with different key nutrient intakes to determine how their impact on weight loss and various cardiometabolic measures.
Hypothesis
The authors didn’t specifically state the hypothesis, but the paper seemed biased in supporting a high-quality diet for beneficial effects on cardiometabolic risk factors.
