Review Article - Journal of Public Health and Nutrition (2019) Volume 2, Issue 3

Lasting effect of nutritional and exercise interventions on body weight: A comprehensive literature review.

¹Department of Obstetrics and Gynecology, Inselspital Bern, Switzerland

²MVZ PAN Institut für endokrinologie und reproduktionsmedizin GmbH, Cologne, Germany

³Quantitative Risikomodellierung, Uhlandstrasse 11, Frankfurt am Main, Germany

Corresponding Author:

Dr. Petra Stute, MD
Section of Gynecologic Endocrinology and Reproductive Medicine
Department of Obstetrics and Gynecology
Inselspital Bern Friedbuehlstrasse 19, 3010 Bern Switzerland
Tel: (0)31-632-1303
E-mail: stutepe@web.de

Accepted date: October 29, 2019

Abstract

Objectives: Obesity is a serious public health concern. The purpose of this comprehensive review is to report on the effectiveness of nutritional and exercise interventions alone or in combination on body weight loss and maintenance in adults.

Methodology: A literature search was performed in 2018. 20 studies on nutritional and exercise interventions were identified and included into this review.

Results: Overall, 18 of 20 studies reported a total weight loss ranging between -0.6% to -9.0%. Diet in combination with exercise yielded the best results, exercise alone was the least effective. High-protein and/or low glycaemic index diets as well as the Mediterranean diet had a highly positive effect on body weight. However, the majority of studies reported body weight regain during follow-up.

Conclusion: Caloric restriction, especially in combination with physical activity, is the most effective way to achieve considerable weight loss in a short amount of time. However, after initial weight loss maintaining body weight in the long-term is a major challenge. Education and cognitive behavioral therapy contribute to long-term success of weight loss programs. Integrating subjective theories for being overweight/obese may improve the outcome.

Keywords

Obesity, Nutritional interventions, Exercise interventions, Long-term weight loss, Weight maintenance.

Introduction

Obesity has become a major public health concern. In 2016, worldwide more than 1.9 billion adults were overweight (body mass index (BMI) ≥ 25) of whom over 650 million were obese (BMI ≥ 30) corresponding to a prevalence of overweight in 39% and obesity in 13% adults, respectively. Obesity does not only affect adults but children as well. In 2016, 41 million children under the age of five years, and 340 million children and adolescents between the age of five and 19 years were overweight or obese, respectively. Overall, the prevalence of obesity increased threefold from 1975 to 2016 [1]. Obesity is associated with an increased risk to develop chronic non-communicable diseases (NCD) such as diabetes mellitus, cardiovascular disease, dementia and cancer. Furthermore, mortality has been shown to be increased in people with a BMI above a certain threshold [2]. As NCD risks increase with increasing BMI [1] weight reduction seems to be the appropriate way to approach these health risks. For most obese people maintaining weight loss is more difficult than initially losing weight. Unfortunately, both, persisting obesogenic environments and physiological adaptations such as reduced metabolic rate and increased appetite can lead to an at least partly regain of the lost body weight. However, it is uncommon that weight regain exceeds starting weight [3].

Thus, it is essential to maintain weight loss over time in order to achieve a long-term decrease in complications of obesity. The objective of this comprehensive literature review was to compare the effectiveness of different lifestyle interventions such as dietary and/or exercise interventions on initial and longterm weight loss.

Materials and Methods

In August 2018, a literature search was performed using the data base Ovid Medline. The literature search was performed using multiple combinations of Mesh-terms and keywords related to the investigated topic. Included terms were “diet”, “nutrition”, “intervention”, “exercise”, “physical intervention”, “weight loss”, “weight maintenance”, “obesity”, “lasting”, “long-term”, “adult”, “follow-up” (Supplementary file 1). The search yielded 192 relevant articles. Only articles from October 2013 to August 2018 were included, since articles published from January 1990 to October 2013 were already covered by one of the included systematic reviews [4]. After application of the above-named time restriction, the final list comprised 43 relevant articles. After August 2018, three additional articles have been identified and included into this review.

Results

Of 46 studies, 20 were included into the comprehensive literature review (Table 1) [4-23]. The other studies were excluded as they, for example: involved participants under the age of 18 years, did not publish the participants’ body weight after the intervention period, or included surgical or pharmaceutical interventions, respectively (Figure 1).

Table 1. Overview of studies included into the review.

Figure 1. Flow chart of literature search and assessment of eligibility.

Study characteristics

Of selected studies (Supplementary file 2), twelve were randomized controlled trials (RCT) [5-12,14-16,21], five were prospective cohort studies [17,18,20,22,23], and three were systematic reviews [4,13,19] including one meta-analysis [19]. Sample size ranged from 18 [17] to 124,988 subjects [13]. Four studies only considered female participants [5,11,21,22]. In general, age range of subjects was broad, e.g. all adults (above age 18) [10, 19], and 18 to 65 years [4,7,13,14,20], respectively, while one study focused on geriatric (age 65-79 years) [18] and another one on younger patients (age 18-35 years) [16]. All but one study (BMI range 21-30) [16] included overweight and obese subjects only. In and exclusion criteria also differed. For example, some studies excluded participants with chronic or severe diseases [6,13,18,20,22,23], BMI above 45 [10], eating13 disorder [20], or hormone therapy [21]. In contrast, others specifically included patients with serious mental illness [17], metabolic syndrome [6], high risk to develop diabetes mellitus [9,23], or physical inactivity [8,10,11,18,20,21]. All but one study [13] provided the duration of intervention ranging from one month [22] to six years [9], and of follow-up ranging from six months [17,22] to almost seven years [5]. Body weight change expressed as relative (%) or absolute change (kg, BMI) was an endpoint in all studies. Additional endpoints comprised changes in body composition [4,5,7,18], abdominal circumference [4,7,10,11,14,22,23], serum lipids [4,7,11,15,23], blood pressure [4,7,8,10,11,14,15,23], and physical activity and nutrition habits [5,8,9,11,15,20,22], respectively. All but two studies (with dietary interventions only [7,13]) examined the impact of dietary interventions combined with exercise on weight loss and weight maintenance, applying either caloric restriction [4- 6,10-12,16,18-22] or not [8,9,14,15,17,23]. Frequently, lifestyle interventions were complemented by, e.g. cognitive behavioral therapy [8,10,20], self-monitoring [6,10,16], and social support and/or motivation [7,10,11,15,23], respectively.

Impact of lifestyle interventions on body weight loss and maintenance

Overall, 18 in 20 studies reported a total body weight loss ranging from -0.6% to -9.0% (Table 2) [5,6]. Of those, 12 studies reported an initial body weight loss but weight regain during follow-up [6-11,14,16,18,19,21,23]. The remaining two studies were systematic reviews and rather compared the effectiveness of lifestyle interventions than individual body weight changes [4,13].

Table 2. Overview of interventions.

Dietary interventions only: A systematic review on the impact of dietary interventions only found a decrease of body weight when choosing beverages such as water, coffee and tea but an increase with beverages such as whole-fat and low-fat milk, and even more with sugar-sweetened beverages and fruit juices [13]. In a more recent RCT [7], diets with either average protein content, high protein content, low glycaemic index (GI) or high GI were compared to each other. During the initial study phase when all subjects simply followed a low-caloric diet body weight decreased by about -11.9%. However, during the intervention and post-intervention phase body weight increased again in all groups ranging from -4.9% to -7.9%. Intergroup comparisons revealed a lower body weight regain in subjects consuming either a diet with high protein content or low GI. Body weight remained stable in participants consuming a diet with high protein content combined with low GI.

Dietary interventions with caloric restriction and/or exercise: Four studies compared various combinations of diet and exercise [4,18,20,21]. Diet in combination with exercise yielded the best results with body weight loss ranging from -2.7% [18] to -8.7% [20], followed by diet only with body weight loss ranging from -2.5% [20] to -6.6% [21]. Exercise alone was only partly effective with body weight changes ranging from +0.1% [18] to -2.1% [21]. During follow-up there was at least some body weight regain in most study arms ranging from +0.1% to +5.8% [18]. Three studies investigated the impact of defined diets in combination with exercise on body weight [5,12,22]. Both, the Mediterranean Diet and the Hypolipemic Diet (lowfat diet) induced a decrease in body weight. Herein, body weight loss ranged from -4.7% [22] to -7.9% [12] with Mediterranean Diet, and from -0.6% [5] to -4.8% [12] with Hypolipemic Diet, respectively. In those two studies, body weight decreased quite fast, while in the third one applying another low-fat diet [5] body weight loss only stabilized at -0.6% at intervention termination after 30 months but then remained stable until follow-up at 80 months. The magnitude of lifestyle changes needed to yield body weight loss was reported by three studies [10,11,16]. Small lifestyle changes included a healthy lifestyle and some exercise merely for enjoyment, whereas large lifestyle changes comprised caloric restriction and moderate-to-high physical activity. Large lifestyle changes induced a body weight loss ranging from -3.3% [16] to -4.4% [10], while small lifestyle changes yielded smaller results ranging from -0.8% [11, 16] to -2.3% [10].

The impact of active body control (ABC) was analyzed by another RCT [6] comparing a low-caloric, low GI diet with and without ABC. ABC comprised telemonitoring of daily physical activity and calorie intake as well as regular individual feedback by experienced coaches. During the first year, diets were complemented with ABC in both groups and total body weight loss was comparable (about -9%). During the second year ABC was only continued by one group. Not surprisingly, body weight regain was lower when ABC was continued (+2.8% vs. +4.4%). Finally, a systematic review and meta-analysis including 45 RCT investigating any lifestyle interventions, food supplements, alternative therapies or pharmacological interventions, alone or in combination, supported the above mentioned results [19]. Caloric restriction was the most commonly recommended dietary intervention and a general increase in physical activity was the most commonly recommended exercise intervention, followed by more specific recommendations such as walking or resistance training. In general, the mean difference in body weight change between intervention and control group at follow-up favored the intervention group ranging from -0.85 kg (at 30 months) to -1.96 kg (at 18 months), respectively.

Dietary interventions without caloric restriction and/or exercise: Dietary interventions without caloric restriction were quite heterogeneous. For example, total body weight loss was greater with the Average Danish Diet (-2.1%) compared to the New Nordic Diet (-1.7%) due to a greater weight regain with the New Nordic Diet (+5.1%) during follow-up [14]. Three studies investigated the effect of what was referred to as “healthy diet” (low-fat, high-fibre diet) combined with a general increase of exercise on body weight [9,17,23]. Total body weight was found to decrease by -0.9% [9] to -4.4% [17] with or without body weight regain during follow-up ranging from +4% [9] to -3.1% [17]. In another RCT, a low-fat, high-fibre dietary intervention was combined with physical activity and cognitive behavioral therapy and compared to diet alone [8]. Total body weight loss was higher in the combined intervention group (-6.7%) than in the diet only and control groups (-1.6% vs. -1.7%), respectively, with body weight regain also being higher in the combined intervention group (+2.6% vs. none). When walnuts (30 g/day) were added as a food supplement to diet and exercise, total body weight loss was lower with walnuts (-3.8%) than with diet and exercise alone (-5.9%). Body weight remained stable in all groups during follow-up [15].

Education and cognitive behavioral therapy: In order to support body weight loss and weight maintenance seven out of nine studies [8,10,12,15-17,20-22] that reported successful further weight loss after the initial weight loss applied educational lessons or consultations with a dietitian [8,10,12,15,17,20,22], partly combined with cognitive behavioral therapy [8,10,20], respectively. Total weight loss ranged from -1.6% [8] to -8.7% [20] with cognitive behavioral therapy having a particularly supporting impact; total weight loss was -6.7% [8], -4.4% [10] and -8.7% [20], respectively, after one year [8,10] and four years of follow-up [20]. Most other studies that included some kind of education [5,9,11,14,18,23] at least partly achieved weigh loss maintenance after a follow-up of up to ten years [9]. This suggests a positive impact of knowledge about nutrition, exercise and lifestyle patterns on long-term weight loss.

Discussion

The World Health Organization (WHO) recommends a diet with limited energy intake from total fats, limited salt and free sugars consumption and an increased intake of fruits, vegetables, whole grains and nuts. For physical activity the WHO recommends to engage in adequate levels of exercise throughout one’s life acknowledging that different types and amounts of physical activity are needed to achieve different outcomes like e.g. body weight control [24]. However, these recommendations are quite general. So, for the individual the question remains which lifestyle intervention is the most effective to accomplish body weight reduction and body weight maintenance.

Our comprehensive review found that: 1) Diet in combination with exercise yielded the best results, diet alone partly achieved good results, and exercise alone was the least effective; 2) Large lifestyle changes induced greater body weight loss while smaller lifestyle changes mainly maintained body weight; 3) Diets with highly positive effect on body weight comprised high-protein and/or low-GI diets as well as Mediterranean Diet; 4) Defined diets like Hypolipemic diet (low-fat), New Nordic Diet, Average Danish Diet, and “healthy diet” were effective for body weight control; 5) Water, unsweetened coffee and tea decreased body weight, whereas sugar-sweetened beverages, fruit juice and milk increased body weight, and 6) Walnuts as food supplement had no or very little effect on body weight.

This supports the findings of a previous systematic review concluding that dietary interventions in combination with exercise are the most effective way for long-term weight loss, followed by dietary interventions only, while exercise alone does not seem to be very effective [2]. In respect to diet type those with caloric restriction are most efficient to induce the greatest body weight loss in a short amount of time (-3.4% [10] to -13.7% [21]). However, in order to achieve long-term body weight loss and body weight maintenance, (considerable) caloric restriction may be not the best solution as most studies reported (significant) weight regain after initial weight loss (+0.9% [11] to +7% [7]). This is not surprising as with total body weight loss also lean body mass decreases which mainly define basal metabolic rate. As a consequence, basal metabolic rate decreases and appetite increases with the resulting hyperphagia leading to an increased lean and fat body mass (collateral fattening) [25]. Thus, long-term maintenance of body weight after initial weight loss is the biggest challenge. Six out of 20 of the selected studies applied several strategies to overcome this problem. Interventions during maintenance phase included education about nutrition [7,10,12,14], social support or motivation [10,23], and further lifestyle interventions (mostly nutritional and exercise interventions in combination) [19]. Total weight loss was >4% in half of those studies [7,10,12], even though there was some weight regain during maintenance phase ranging from +0.8% [10] to +7% [7]. This indicates that cognitive behavioural therapy might increase patients’ adherence to the weight loss program as well as support a sustained long-term change of behaviour patterns.

The strength of our review is to provide a comprehensive overview on different (combined) interventions to reduce and then maintain body weight. It also highlights that counselling patients about realistic results of weight loss programs is essential in order not to avoid feelings of failure. Obviously, this review also has some limitations. Study designs including sample sizes, cohorts’ characteristics, investigated interventions, intervention duration and follow-up were heterogeneous making it difficult to compare initial and long-term effectiveness of interventions. Accordingly, studies with a short follow-up period of e.g. six months achieved better results than studies with a long followup period of three years or even more as weight regain would not be registered in the former studies. Furthermore, in some studies results were either generalized [7,19], pooled [13] or only displayed in graphics and therefore not very exact [5,7,9]. For the individual, it is hard to predict which strategy for body weight maintenance would fit best. For example, illness perception in people with overweight or obesity has been shown to differ [26]. Accordingly, the predominant theories for being overweight/obese were health behaviour and psychosocial factors. Overweight/obese people with psychosocial theories on illness causes were more likely to have emotional or disinhibited eating patterns. Furthermore, cognitive control of eating patterns increased with age in both sexes. Thus, successful weight reduction programs should integrate subjective illness perceptions to improve therapeutic outcome, preferably right from the weight loss program start.

Conclusion

In conclusion, caloric restriction is the most effective way to achieve considerable weight loss in a short amount of time, especially in combination with physical activity. However, after initial weight loss maintaining body weight in the longterm is a major challenge. Adjunct education and cognitive behavioural therapy contribute to long-term success of weight loss programs. In addition, integrating subjective theories for being overweight/obese may improve the outcome.

Acknowledgements

The authors would like to thank the secretary J. Wilhelm for her administrative support.

Conflict of Interest

All authors declare that they have no conflicts of interest with the contents of this article.

Authors’ Contributions

Tiziana Marti: Literature search, manuscript writing; Dolores Foth: manuscript editing and advice; Susanna Weidlinger: manuscript editing and advice; Volker Stute: manuscript editing and advice; Petra Stute: project development, supervision, funding, manuscript editing and finalization.

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