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What diet is best for long-term weight loss?

Updated: Jul 1, 2023

There are innumerable diets on the market today claiming to offer fast and effective weight loss. But which one to choose?


The number of people struggling with excess weight has risen sharply in recent years. As a result, there is an enormous market for diet programs, books, and products - all claiming to help people lose weight quickly and easily. While some of these diets may prove successful in the short-term, long-term success is considerably more elusive.


As it turns out, there may not be one, single most effective diet for losing weight. With so much conflicting information out there, it can be hard to determine which approach is best, when trying to achieve lasting results. In this article we will explore what research has revealed about common diet choices and their ability to lead to sustained weight loss over time.


Is the Yo-Yo effect on weight harmful to your health?


Most people trying to lose weight have, at some point of their lives, experienced what is known as "weight cycling", also known as "yo-yo dieting". It consists of cycles of restrictive eating followed by periods of overindulging. It is surprisingly common. Around 20-35% of men and 20-53% of women, including people at a healthy weight, engage in this type of dieting, at some point in their lives.


According to research conducted by Dr Heymsfield and collaborators, when we start losing weight, an initial quick phase of weight loss occurs by burning glycogen stores, protein and water. As the body starts burning fat instead, the weight loss slows and tends to plateau at about 3-6 months.


Multiple studies have been conducted to determine if cycling through weight gain and weight loss has any hazardous health effects or if it negatively affects our metabolism. To date, there is limited evidence of harm yet results remain inconclusive. Current guidelines do not discourage people in their attempts to achieve weight loss. However, research does suggest that yo-yo dieting may lead to negative psychological effects such as depression, anxiety, and dissatisfaction with one's body. Overall, it would be best to avoid.


Certainly, there are numerous benefits that come with losing excess weight. The Diabetes Prevention Program has indicated that even a 5% reduction in body weight, followed by maintaining it, leads to health benefits. Unfortunately, it is common that individuals who diet end up at a higher weight than they began.


Why is it so difficult to maintain weight loss?


While dietary restrictions may lead to success initially, they may be inefficient in the long-term maintenance of weight loss. This is because biological changes happen in our bodies when we limit our caloric intake. Environmental and behavioral factors will also influence our successes or failures in maintaining weight loss. Together, they pose significant challenges for individuals who want to remain at a lower weight.


A study by MacLean et al. described this process very thoroughly in their work entitled: "Biology's response to dieting: the impetus for weight regain" and concluded that strategies used for preventing weight regain need to be comprehensive and persistent, to counter both powerful biological adaptations and environmental factors to achieve sustained long-term weight loss. Fortunately, subsequent research demonstrates it is an achievable goal.


How to achieve long-term weight loss with a specific diet


According to research, successful weight loss requires making lifestyle changes that balance energy intake and output. Contrary to what many people think, energy balance is more complicated than just "calories in/calories out".


The food we consume will be converted to energy (or heat) that is measured in calories. Our daily calorie intake comes from carb intake, protein and fat intake.


It is difficult to determine the "energy output" which is vital to maintain our body's vital functions:

  • "Resting Metabolic Rate" refers to the energy our bodies need even when at rest and may represent 50-70% of total daily energy expenditure.

  • "Physical activity" is divided into these categories:

(a) Purposeful Exercise

(b) Non-Exercise Activity Thermogenesis (NEAT) which is the energy expended for everyday activities that cannot be voluntarily controlled, such as fidgeting, for example.

  • "Thermic Effect of Food" refers to the energy needed to digest the food we eat which represents about 10% of the total energy expenditure.

According to the equation above, for achieving steady weight loss, a decrease in daily food intake and an increase in total energy expenditure is required.


Metabolic Adaptation and the Benefits of Exercise


When an individual sheds pounds, their basal metabolic rate and non-exercise related energy expenditure both decrease. This may be attributed to the fact that lighter weight and reduced muscle mass require less energy for bodily movement. Researchers have also observed that after weight loss, people's metabolism can slow down more than expected for the amount of body mass lost. This process is known as "metabolic adaptation". To counteract the metabolic adaptation, we must find ways to increase our metabolism. Perhaps the best known way is to exercise.


Research indicates that physical activity may raise our awareness of feeling full after eating a meal. Furthermore, it can enhance insulin sensitivity, reduce inflammation, and boost our mood. While it alone may not be an effective weight loss strategy, it is helpful for maintaining a healthy weight and to our overall well-being.


The Look Ahead trial provided further proof of the benefits of exercise. This was an extensive study involving over 5,000 people with excess weight and Type 2 diabetes. This study intended to assess the effects of an intensive lifestyle intervention on important health outcomes. This research provides the largest and longest randomized evaluation to date of an intensive lifestyle intervention for weight reduction. The participants in the study were monitored for an average of 9.6 years. Upon completion of their program, 39.3% of individuals who lost 10% body weight in the first year were able to sustain their weight loss eight years later. Among the participants, 25.8% retained a 5-10% decrease in weight after eight years.


The persons who were most successful in losing and keeping the weight off had one thing in common--they exercised more often, watched their calories, and weighed themselves daily or on a regular basis. It is important to mention that as part of the study protocol, researchers implemented lifestyle interventions that emphasized not only dietary changes and exercise, but also the importance of managing our thoughts as they recognized the link between our thoughts, feelings and actions. Participants were taught how to control their eating behavior such as limiting eating locations and meal timing, addressing negative mindsets, and avoiding relapse.


Conclusion


There are many popular diets for weight loss such as high-protein diet, high-fat, low-carb diet, low-fat diet, paleo diet, vegan diet or vegetarian diets, no refined carbohydrates, fiber-rich foods, intermittent fasting or time restricted feeding, alternate day fasting, avoiding processed foods, and DASH diet, to name a few.


Establishing realistic goals is essential when choosing a diet. We must ask ourselves: Is this the kind of food I want to eat for the rest of my life? Is this a balanced diet for me? Is it a healthy diet for my body?


As we learned from the studies mentioned in this article, maintaining weight loss is not just about diet. The key to success involves limiting caloric intake for the long term, increasing physical activity to boost metabolism, weighing yourself regularly and learning how to manage thoughts and emotions. In the end, all these changes will contribute to personal growth, leading to a new version of yourself.


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