Dietary guidelines have changed over the years as research becomes more accurate in determining what we should eat to attain optimal health and weight. The strongest evidence to date shows that calories matter, but focusing on food quality is an equally important part of preventing weight gain and promoting weight loss.
Some dietary approaches are based on certain food choices and/or restrictions they impose. This can take the form of advising specific foods or food groups from which to base the diet on or naming specific foods or food groups that should be avoided outright. This blog will examine some of the most common approaches of this type.
Mediterranean Diet
The Mediterranean diet was originally conceived based on observations of the good health experienced by populations living by the Mediterranean (predominantly Greece, Italy, and Spain).
Plant foods such as fresh vegetables, fruit, grains, and nuts make up the basis of the diet in addition to liberal use of olive oil. Fish, poultry, and dairy like cheese and yogurt are included in moderate amounts while red meat consumption is low.
However, the Mediterranean diet extends beyond food choices as it also accounts for social and cultural aspects such as communal mealtimes, resting after eating, and regular physical activity.
The Mediterranean diet has been studied extensively for its ability to promote heart health. In fact, research shows that the Mediterranean diet may even be linked to a lower risk of heart disease and stroke.
One study compared the effects of the Mediterranean diet and a low fat diet and reported that the Mediterranean diet was more effective at slowing the progression of plaque buildup in the arteries, which is a major risk factor for heart disease.
Other research shows that the Mediterranean diet could also help lower levels of diastolic and systolic blood pressure to support heart health.
ADVANTAGES
Reduced risk for many chronic diseases
Decreased mortality (death) rate
Potential weight loss
DISADVANTAGES
May require additional food prep time
Red wine should be consumed in moderation
Potentially difficult adherence
Vegan Diet and Vegetarian Variations
A vegan diet is a plant-based diet that excludes all animal products, including meat, fish, eggs, and dairy. There are a number of other dietary approaches that limit or restrict the consumption of animal products to varying degrees.
Vegetarian diets can improve blood glucose levels in diabetics but they are not superior to other dietary approaches and are potentially inferior to other options such as the Mediterranean diet.
A diet centred on plenty of whole, minimally processed plant foods lowers your risk of heart disease and benefits your overall health.
Vegetables, fruit, legumes, whole grains, nuts and seeds are low in saturated fat, contain heart-healthy fats and are an excellent source of fibre. They give our bodies vitamins, minerals, antioxidants and phytochemicals, which offer protection against disease.
ADVANTAGES
Reduced risk of heart disease and cancer
Improved blood glucose levels in diabetics
Potential weight loss
DISADVANTAGES
Potential for inadequate protein intake
Risk for suboptimal vitamin B12, calcium and iron intake
Risk for suboptimal omega-3 fatty acids and creatine intake
Potentially difficult adherence
Paleo Diet (Paleolithic Diet)
The paleo diet is a dietary approach that focuses on selecting foods that proponents of the diet claim humans were exposed to for most of our evolutionary history: meat, fish, vegetables, fruit, nuts, and seeds. In its strictest form, it calls for the avoidance of grains, legumes, dairy products, and most conventionally processed foods.
However, this commonly represented list of foods is not in concordance with the current evidence of what our ancestors likely consumed.
It is clear that "Stone Age" humans did eat a variety of high-quality foods that were rich in nutrients and fiber. Compared to this diet, modern diets provide much less variety and are loaded with artificial sugars and salt. Since it is impractical to mimic the exact diet that our Stone Age ancestors ate, we can reasonably take some key foods and adapt them to a modern lifestyle.
ADVANTAGES
Weight loss
Improved blood markers (e.g., cholesterol, triglycerides, insulin)
Decreased consumption of hyperpalatable (sugary, salty, fatty) foods
DISADVANTAGES
Unnecessarily restricts healthful foods (e.g., whole grains, legumes, dairy)
Does not appear superior to other diets for weight loss
Potentially difficult adherence
Gluten-Free Diet
Gluten is the term used to describe a collection of proteins found in grains. In wheat, gluten covers two related proteins: gliadin and glutenin.
Other gluten-containing grains include (but are not limited to) barley and rye. Naturally gluten-free grains include (but are not limited to) corn and rice.
For a long time, a gluten-free diet has been prescribed in clinical practice for the management of patients with celiac disease as well as a wheat allergy. In celiac patients, the body amounts a severe immune response to the gluten proteins. This causes severe damage to the gut lining and patients exhibit several symptoms, including gastrointestinal distress, diarrhea, pain, rapid weight loss, and severe fatigue. It is treated with a gluten-free diet for life.
Although the gluten-free diet has been purported to aid in weight loss, for those with celiac disease, it may actually cause weight gain. For some, this can be desirable, particularly if weight loss was a symptom preceding diagnosis. But for others, the gluten-free diet may exacerbate existing overweight or obesity.
ADVANTAGES
Removes Gl distress for individuals with celiac disease
May improve GI distress for individuals with a gluten intolerance
May be beneficial for those with hashimoto's thyroiditis
DISADVANTAGES
Inferior to many other diets for weight loss
Inferior to many other diets for improved health markers
Potentially difficult adherence
MyPlate
MyPlate is the most current attempt from the USDA to represent guidelines for healthy eating through a visual representation with supporting recommendations. MyPlate is the latest in a long line of such representations by the USDA, including the 2005 MyPyramid and the 1992 Food Guide Pyramid (A Brief History of USDA Food Guides, 2017).
The MyPlate recommendations are based on four primary goals:
Focus on variety, amount, and nutrition.
Choose foods and beverages with less saturated fat, sodium, and added sugars.
Start with small changes to build healthier eating styles.
Support healthy eating for everyone.
Despite increasing knowledge of healthy eating guidelines, as with virtually all diets, adherence to these dietary guidelines still seems to be a problem at least at a population level.
It’s important to eat a variety of fruits, vegetables, grains, protein foods, and dairy and fortified soy alternatives. Choose options for meals, beverages, and snacks that have limited added sugars, saturated fat, and sodium.
ADVANTAGES
Simple to use
Visual
Balanced
DISADVANTAGES
Uses estimates
Combination foods are difficult
DASH (Dietary Approaches to Stop Hypertension) Diet
The dietary approaches to stop hypertension (DASH) diet was originally developed to help people lower blood pressure without medication.
The DASH diet is based around a small number of very simple recommendations. Overall, the DASH diet promotes the inclusion of many health-promoting foods and would be a healthy eating approach if adhered to.
As is a running theme with all the diets discussed so far, the benefits of the diet for health and body composition are simply a function of eating primarily minimally processed foods and consuming appropriate energy intake.
While the DASH diet was originally developed as an eating style to help lower blood pressure, it has been found to be a fabulous plan for weight loss.
ADVANTAGES
Reduced blood pressure
Improved overall cardiovascular health
Potentially can reduce body weight and body fat
DISADVANTAGES
May require additional food-prep time
The primary emphasis is lowering blood pressure not body weight
Potentially difficult adherence
Summary
A wide variety of different dietary approaches can lead to improvements in health and body composition. Rather than asking “Which diet/method is best?” it is more important for you to understand the principles that underlie a healthy diet and/or a diet that alters body composition.
In fact, all dietary approaches or methods will be successful for the same reasons. For example, for body fat loss to occur, it is advisable that the diet has an energy (calorie) content that places the dieter in a caloric deficit, contains an adequately high amount of protein, and is based on predominantly minimally-processed foods. Clearly, the diet could be set-up in many ways to achieve such principles.
Some dietary approaches have much stronger evidence behind their efficacy than others. For example, the Mediterranean diet and the DASH diet have an extensive amount of peer-reviewed literature behind them with the vast majority showing clear benefits for health. Other diets do not have extensive, high-quality long-term research supporting their use.
When diets are matched for calorie and protein content, there seems to be no fat-loss advantage for either low-carbohydrate or low-fat diets. Therefore, it is advisable to use amounts of carbohydrates and dietary fat in the diet that fit the individual’s preferences and goals. Similarly, current evidence suggests that in diets matched for calories and protein, the impact on body composition will be similar between diets of differing meal timings and meal frequencies.
Dietary restraint is required for successful outcomes, particularly in relation to weight loss. However, it is likely that a flexible control of diet behaviors is superior to a rigid control, as it leads to less overeating and negative psychological outcomes. For most individuals, foods and/or food groups should not be unnecessarily restricted.
No matter the exact approach, current evidence indicates that a healthy diet is one based on vegetables, fruit, whole grains, lean meats, fish, eggs, nuts, seeds, dairy, and legumes. For body composition specifically, calorie intake and macronutrient intake will be the main drivers of change. Food type/quality has a very minor role in impacting body composition from a physiological perspective. However, in practice, a diet of predominantly whole, minimally-processed foods will lead to better outcomes indirectly due to the increased probability of controlling calories on such a diet.
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