Diets for weight loss Scientific Approach

 


 

Obesity has become one of the major problems around the globe, due to inappropriate eating habits and quality of life. It may lead to many medical issues that may be serious and sometimes lethal conditions.

Modern diet plans designed to control obesity and weight issues are majorly based on individual experience and material from different magazines and books, without scientific proof.1

Animal and human clinical trials had conducted to observe the changes in the body and metabolism to determine the most appropriate dietary options. However, the trials show numerous limitations and outcomes should be critically observed.1

No dietary option has shown promising results for weight loss while for temporary solutions, high-keto, low-carb options and intermittent fasting are opted to promote weight loss and could be used as a first step for the journey. However, adverse effects may be observed, hence caution is required.1

Different types of Dietary regimes commonly followed are as follows:

 

·         Low-Caloric dietary regime:

This targets to decrease the daily caloric intake by 500–750 kcal. For this dietary regime of 1200–1500 kcal/d for females and 1500–1800 kcal/d for males is adequate. Low caloric diets normally are low-fat diets also and commonly macronutrient composition is 20% protein, 30% fat, and 50% carbohydrate. The saturated (animal) fat should be reduced and fiber-rich foods such as fruit and vegetables should be increased. While the low caloric diets are moderately useful for short-term effects on the body, individual responses to these diets are heterogeneous and continuous usage of this regime is very difficult.2

 

·         Low-Fat dietary regime:

A low-fat diet is considered a safe and sound method for weight loss for a long time on the basis of the following observations:

o   Energy from fat is less than energy from carbs, and a high fat/carb ratio in the dietary regime may lead to obesity in the individuals.2

o   fat is more easily absorbed from the gut as compared to carbs hence preventing energy loss in terms of unabsorbed nutrients.2

o   Carbs are more blazing than fat and energy utilization is lower in a diet having a high fat/carb ratio than a diet with a low fat/carb ratio.2

o   A high-fat diet may damage the intestinal lining and intestinal microflora resulting in abnormal metabolism and irregular body weight. Furthermore, 1gm fat provides 9kcal while 1gm of carbs provides 4 kcal which is why a low-fat diet is more beneficial.2

despite the above-mentioned facts, different clinical trials and meta-analyses show that a low-fat diet did not show any superior effect in the long-term weight loss when compared to other diets.2

 

·         Low-Carb dietary regime:

A low-carb dietary regime is derived from the ketogenic Atkins diet in which carb intake was restricted to <30 g/day this is why it is considered as a low-quality dietary approach. While in modern low-carb dietary approach daily intake is less stringent and fiber is also added to the regime. According to the Meta-analyses, low carb diets are more potent for short-term weight control as compared to long-term effects.

A low-carb dietary regime has been newly implemented in Greece namely the “Euro diet” and it is based on four continuous phases with the introduction and reduction of different carbs.2

 

·         High-Protein dietary regime:

Protein is 20% to 30% of our daily intake, clinical studies have shown that in obese individuals high-Protein diet provides 3.8kgs of weight loss over the time of 6 months which is higher if compared to a high-carb diet. While studies have shown that obese female individuals with a high dietary protein to carb ratio provide positive effects on body composition, blood profile(lipid), and glucose stability in the body. Maybe these effects are observed partly by effects on satiety and a lower glycemic load due to lower carb utilization.2

Dietary regimes high in protein may have a differential amount of saturated fatty acids and nutrients, and there are concerns that high-protein diets may affect serum lipids and increase the chances of CVD events (cardiovascular diseases). furthermore, high-protein diets, especially animal source proteins may increase the chances of diabetes mellitus, atherosclerosis, and nephrolithiasis and continuous usage may lead to renal (kidney) damage. Hence diet can be partially replaced with refined carbs & proteins that contain a low amount of saturated fatty acids.2


 Formula Dietary regime:

Formula diet provides a better energy control than hypocaloric dietary regimes and they are called very-low-calorie diets (VLCD, <800 kcal/day) or low-calorie diets (LCD, 800–1200 kcal/day). Formula diet comprises nutrient-enriched bars, liquids, and beverages, which are low in card and fatty acids and rich in vitamins, minerals, and proteins which provide a reduction in energy and lead to the weight loss of 10–20 kg within 8–12 weeks. After the initial instant weight loss, many things can be done to make this body weight persistent and prevent it from regaining i.e., high-protein diets, medicines, meal replacements, and exercise regularly.2

This should be noted that the formula diet is not for long-term use it should be subsided after 12 weeks, there are numerous adverse events that have been seen so caution should be taken.

 

·         Mediterranean Dietary regime:

According to the DIRECT study (Dietary Intervention Randomized Controlled Trial), the Mediterranean diet is more effective than a low-carb and low-fat diet in a controlled wok setting. Other data shows that Mediterranean food products for example extra-virgin olive oil and nuts can decrease the chances of major cardiovascular events. The Mediterranean diet shows promising results in the population of Spain, while the effect of the Mediterranean diet on long-term weight control needs to be investigated through additional clinical studies conducted over a longer span and in different nations around the globe.2



 

Intermittent dietary regime:

The Intermittent energy restriction (IER) is a restriction of meal consumption, with intervals between the decreased energy intake and feeding without restrictions. The most frequently followed procedures of IER are restriction on two consecutive days per week, while on an alternate day 60–70% energy and fasting on alternate days (intermittent fasting, IF), there are very limited clinical proof present to support IER while few available randomized clinical trials comparing intermittent dieting regime with continuous hypocaloric diets in overweight and obese subjects, shows the same amount of weight loss for a period up to 6 months.2

IER is more likely preferred as compared to complete intermittent fasting, because of better tolerability, less stressfulness, and minimal metabolic fluctuations (free fatty acid and ketone fluxes). Furthermore, it may anchor many side effects and more clinical evidence is required to prove its effectiveness.2

 



The ideal diet for obese and overweight people is defined as being safe, potent, healthy, full of nutritional values, and pocket friendly. It should effective for long-term weight loss. While in numerous clinical trials, reviews, and meta-analyses different diets with contrasting caloric values and compositions have been aimed and results are encouraging for weight loss in adults. Nevertheless, the adequate dieting regime remains debatable.2

Scientific data about the ideal healthy dieting regime is both persistent and to the point: The ideal healthy dieting regime is rich in fruits, vegetables, whole-grain products and high-quality proteins and poor in added carbs,  grains(refined), and tin/processed foods. Individuals adopting the aforesaid diet may easily control obesity without becoming a calory counter or limiting the daily food intake. exercise and utilization of energy/calories play an adequate role in weight loss.2

 

References: 

1. Nutrition 2020 Jan;69:110549.  doi: 10.1016/j.nut.2019.07.001. Epub 2019 Jul 4

          Link: https://pubmed.ncbi.nlm.nih.gov/31525701/

2. Healthcare 2018, 6, 73; doi:10.3390/healthcare6030073

Link: Healthcare | Free Full-Text | Defining the Optimal Dietary Approach for Safe, Effective and Sustainable Weight Loss in Overweight and Obese Adults (mdpi.com)

Comments

  1. Health is wealth is such a profound statement. I have worked as a Community Nutritionist for years in low income communities.

    Sensible eating and regular physical activity is the only key to weight-loss. But if one does have the motivation, drive and consistency to live a healthy life, they will never reach their weight-loss goals. Most low income families rely on fast food and dollar store groceries to feed their family members.

    We all know that these food sources are high in unhealthy fat, simple sugars and very low in Nutritional value. Knowledge is power, but financial stability also goes long way. Great article.

    ReplyDelete

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