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Effects of meal frequency on

weight loss, hunger, and satiety in women

 

 

Katsiaryna Molnar

Dr. Michael Patterson

 

 

 

MF – Meal Frequency

BMI – Body Mass Index

VAS – Visual Analogue Scales

FEO – Frequently Eating Overweight/obese participants

SEO – Seldom Eating Overweight/obese participants

FEH – Frequently Eating Healthy participants

 SEH – Seldom Eating Healthy participants

 

 

 

Key words: Meal Frequency, Weight loss, Appetite, Hunger, Satiety

 

Word Count: 3,996

 

 

University of Roehampton, 2020

Abstract

 

Background

Eating more frequently has been reported to be related to a greater weight loss and favorable impact on appetite regulation.

Objective

The purpose of this randomized controlled trial pilot study was to examine the effect of a small change in meal frequency on weight loss, hunger and satiety during 28-day dietary intervention under identical conditions in women population.

Design

Two online parallel studies were carried out in this trial. A total of 35 overweight/obese women (age 38±8 years; BMI 30±4kg/m2) were randomized for Study 1 checking the impact of higher meal frequency on weight loss. The participants were given an identical moderately restricted in calories and higher in protein diet, and split into two groups: frequent eaters (4-5 meals a day) and seldom eaters (3 eating occasions a day). For Study 2, observing the correlation between increased meal frequency and hunger/satiety sensation levels, 26 healthy-weight (BMI 23±2 kg/m2) females, aged 35±5, were recruited. They also were divided into 2 groups according to the frequency (4-5 vs 3 meals/day) of an identical balanced eucaloric diet.

Results

The overweight/obese women had a significant weight loss after 28-day of dietary intervention (3.15±1.66 kg, p=0.001), but the difference between frequent and seldom eaters was not significant (p=0.980). Similarly, no any significant positive effect on hunger or satiety sensations was found in healthy-weight participants with higher vs seldom meal frequency. In contrast, lower meal frequency resulted in a significant increase of satiety rating in healthy-weight individuals (p=0.034).

Conclusion

Collectively, the findings of the present study suggest that in overweight/obese women eating 4-5 or 3 times a day does not significantly differ in relation of weight loss in kilograms. Furthermore, the present trial detected that higher meal frequency also doesn’t influence hunger and satiety, whereas lower meal frequency resulted in significant satiety improvement.

 

 

 

 

Introduction

Obesity remains a predominant public health concern. In recent decades, it`s prevalence has been rapidly growing worldwide, and nowadays has reached global epidemic proportions. In 2016 more than 1.9 billion adults were overweight or obese (WHO, 2018). The extent of risks associated with obesity has been highlighted in many countries. Increased risk of diabetes, high blood pressure, liver disease, gall bladder stones, coronary artery disease, cerebrovascular disease, psychological dysfunction, OSA, osteoarthritis, certain types of cancer, and infertility (Abdelaal et al., 2017).

A vast number of studies have been already undertaken to understand weight management in humans. One of the concepts, increasing meal frequency (MF) was proposed about 40 years ago, and since many large observational studies observed a favorable effect of increased MF on body weight and adiposity (Faby et al., 1964; Metzner et al., 1977; Drummond et al., 1998; Ma et al., 2003). Furthermore, numerous experimental trials have demonstrated evidence of increased MF benefits on body weight management, metabolism, and health (Palmer et al., 2009). It has been hypothesized, that the phenomenon of more frequent eating brings greater appetite control, improved glucose homeostasis, and increased food thermic effect (Schoenfeld et al., 2015). Alongside this, it has been shown that frequent macronutrient intake, particularly increased proteins, can beneficially contribute to lean mass development (Areta et al., 2013), enhancement of resting metabolic rate (Leidy and Campbell, 2011), and consequent fat mass reduction (Anciero et al.,2013).

However, there were several arguing reports from observational studies showing no association between food frequency occasions and body weight or body fatness (Kant et al., 1995; Yannakoulia et al., 2012). Some studies contrastingly stated that higher MF is associated with excess body weight and obesity (Howarth et al., 2007). Furthermore, several pilot studies did not observe a substantial difference in weight loss regarding various meal frequency (Berteus Forslund et al., 2008; Cameron et al., 2010). In contrast, some trials have suggested that a longer gap between meals and having fasting periods are beneficial (Stote et al., 2007; Kahleova et al., 2014; Gabel et al., 2018). The researches explained that in terms of weight loss the longer gaps between consuming foods spontaneously reduce daily caloric intake without calorie counting, and regarding health benefits, these gaps stimulate autophagy – the essential process to tackle cellular stress and save normal cell function (Paoli et al., 2019).

In addition, in recent years, concerning the mentioned appetite control in obesity management, there has been increasing interest in understanding hunger and satiety mechanisms (Suzuki et al., 2012). Numerous studies have been carried out to estimate the impact of MF on these complex body processes. While many trials have demonstrated that consumption of small, frequent meals positively affect appetite control (Louis-Sylvestre et al., 2003; Bachman and Raynor, 2012), others have stated the controversial concept, supporting the absence of significant evidence of mentioned association (Perrigue et al., 2016; Ingves et al., 2017). What is more, some studies have shown the opposite results, where increased meal frequency elevated feelings of hunger and desire to eat of examinees (Ohkawara et al., 2013).

Therefore, firstly, the present randomized control trial aimed to check the controversial hypothesis that increasing meal frequency results in higher efficacy of body weight reduction in comparison with a lower meal frequency under identic conditions. The difference between 3 and 4-5 eating occasions was examined in the present trial since the studies in previous literature focused on 1-3 meals a day versus 6 and more meals a day (Schoenfeld et al., 2015), thus little is known whether there is a difference in meal frequency effects if adding 1-2 meals only. Secondly, to discover whether a greater MF (also, the difference only in 1-2 meals) affects appetite and satiety sensation, particularly fasting and postprandial hunger and satiety levels at the baseline and in 4 weeks.

 

 2. Materials and methods

 

2.1 Study design

This parallel-group, randomized controlled pilot study was carried out in online mode from first to 28th of June 2020 in women population from different countries in two languages (English and Russian). Participants were assigned to higher (4-5 times a day) or rarer (3 times a day) meal frequency according to their will and dietary habits (most of the participants did not change their habitual frequency of eating).

 

2.2 Participants

Eighty-four females from 18 to 60 years old without serious health problems or special health conditions were recruited via an advertisement in social networks, with BMI more than 25 for Study 1, and with BMI between 18 and 25 for Study 2. The participants were screened online for any health problems by the standard checklist. At the screening, the individuals` height and weight were self-reported and body mass index (BMI) was calculated. Participants with BMI<18 and were excluded, as well as pregnant and breast-feeding women and volunteers with chronic diseases, which could affect the outcomes. All the recruited participants signed the Consent Form approved by Roehampton University, London. Of 84 participants, taken to the experiment, 23 withdrew after the start, and 61 completed it, whose results are presented herein.

 

2.3 Experimental procedure

The whole experiment was undertaken online over 28 days in two parallel Studies. Study 1 was checking the association of Meal Frequency (MF) and weight loss hypothesis, whereas Study 2 was discovering the effects of different MF on hunger and satiety ratings.  For both Studies on Day0 (baseline, before the start) and Day29 (control day, after the completion) the participants filled up the detailed questionnaires.

The questionnaires contained: Personal details (name, age, place of living, physical activity level); Self-reported anthropometric measurements (height, weight, waist, and hip circumferences); Visual Analogue Scales (VAS, Flint et al., 2000) for Hunger and Satiety self-assessments at 3 points a day (10 minutes before breakfast, lunch and dinner – for hunger, and 10 minutes after breakfast, lunch, and dinner – for satiety). The 0-meaning for hunger self-assessment was “not hungry at all”, and meaning at value 10 was administered as “starving”. For estimating satiety sensation, value 0 meant “not full at all, would eat the same amount”, and “ate too much, feel nauseous” – for grade 10; VAS for reporting the diet compliance on Day29. VAS was performed by scale from 0 to 10 for choosing relevant diet adherence, where value 0 was “I have not followed the given diet at all” and value 10 was “I have been following the diet very strictly”.

To avoid the limitation due to the impact of different levels of physical activity on weight loss (Swift et al., 2014), all the participants were recommended to apply 150 minutes a week of any exercise. Furthermore, for achieving better experiment’s diet adherence, before the start and every week of the experiment, the researcher discussed difficulties and questions regarding the trial on Webinars and was in touch with the participants via email and social channels every day of the study.

 

 Study 1

Thirty-five overweight or obese (BMI >25 kg/m2) females were observed in Study 1. All the subjects for 4 weeks were following the identic moderately restricted (1500-1700 kcal/day) higher in protein hypocaloric diet (Supplementary Data) split by 4-5 or 3 meals. The women were divided into two groups accordingly to the willing type of meal frequency: Frequently Eating Overweight/obese individuals (FEO) and Seldom Eating Overweight/obese individuals (SEO), n=18, and n=17 respectively. Anthropometric measurements, such as height, weight, waist, and hip circumferences, were self-reported at baseline (Day0) and in 4 weeks (Day29) in the given questionnaires. Alongside this, the volunteers were examined regarding hunger and satiety rates via VAS.

  

Study 2

Twenty-six healthy-weight (BMI 18-25 kg/m2) females took part in the second study of the trial. All the participants were given the identic eucaloric balanced diet for weight maintenance, and were organized into two groups relevantly to the type of meal frequency: Frequently Eating Healthy individuals (FEH, n=10) and Seldom Eating Healthy individuals (SEH, n=16). The imbalance in the number of participants in each group occurred due to the volunteers withdrawing. The diets of each group can be seen in Supplementary Data. For analyzing hunger and satiety levels around three main meals the rating system (VAS) was performed in the questionnaires, which the participants filled up at baseline and control day after 4 weeks.

 

2.4 Diet

All types of diets were developed by using DietPlan software (Version 7). In both studies, the first meal of a day (breakfast) was introduced within 1 hour after waking up and the last meal (dinner) was applied no closer than 3 hours before sleep. This is due to the meal timing concept, which has been vastly studied to play a substantial role in obesity and metabolic health (Xiao et al., 2019; Kahleova et al., 2017). Furthermore, we applied a greater amount of protein in the diet (25-30% of daily energy intake) for Study 1, as earlier scientists observed significantly higher total and abdominal fat loss in those who consumed an increased in protein diet (Anciero et al., 2013). Also, the weight loss diet had a moderate (300-500), but not a large calorie deficit, to minimize lean mass losses (Bopp et al., 2008). 

For FEO and SEO groups the energy-restricted diet was designed, identic in kcal and macronutrients, but split into 4-5 or 3 meals respectively. The diet contained between 1500-1700 kcal, with 30% of the protein in total energy intake, 30% of fats, and 40% of carbohydrates. For FEH and SEH groups the identic eucaloric diet, split into 4-5 or 3 meals accordingly, was developed. The energy maintaining diet contained 1800-2000 kcal with a balanced formula of macronutrient distribution: 20% proteins, 30% fats, 50% carbohydrates were applied (see Supplementary Data).

 

2.5 Statistical analysis

All data from the Initial (on Day0) and Final (on Day29) questionnaires were placed into the Excel file, where several formulas were applied to count needed results, such as BMI=weight/height2, (on Day0 and Day29); Wight loss in kg = Weight on Day0 – Weight onDay29; Weight loss in % of body mass = Weight loss in kg x 100 / Weight on Day0; Excess body weight = Height 2 / 10000 x (-25-(-BMI)), (on Day0 and Day29); Weight loss in % of Excess body weight = Weight loss in kg x 100 / Excess body weight; Waist/Hip ratio = Waist circumference / Hip circumference (on Day0 and Day29); Mean hunger (throughout a day) = (Hunger rate before breakfast + Hunger rate before lunch + Hunger rate before dinner) / 3; Mean satiety (throughout a day) = (Satiety after breakfast + Satiety after lunch + Satiety after dinner) / 3; Where Weight loss in kg in overweight/obese participants was more than their Excess weight in kg, the outcome “Weight loss in % of Excess weight” was counted as 100%.

IBM SPSS Statistics software for Windows, Version 26 was used for analyzing the study`s outcomes.

For the first study in overweight and obese participants, to understand whether the reduction of body weight was significant or not after the 28-day diet intervention, the paired t-test was applied for values of Excess body weight on Day0 and Day29. Furthermore, the independent student t-test was used for comparison of the weight changes (in the percentage of both body mass and excess body weight) in the groups with different meal frequencies (FEO and SEO). In the second study, to compare hunger and satiety levels at baseline and control day around the main three meals in two healthy-weight groups with different MF (FEH and SEH), a paired t-test was applied to the values of Mean Hunger on Day0 and Day29. The same was administered in overweight/obese individuals (FEO and SEO groups) for additional outcomes. In addition, by ANOVA-test was identified the difference in mean hunger and satiety rates on Day29 between all four groups.

 

 3. Results

 3.1 Participant characteristics      

Sixty-one women out of 84 recruited have completed the experiment. Most of the volunteers were from the Republic of Belarus (68,9%) and the UK (18%), the remaining distributed between Russia (9,8%), Hungary (1,6%), and Singapore (1,6%). Thirty-five subjects with BMI more than 25 were participating in Study 1, and 26 healthy-weight women were observed in Study 2.

 

Study 1. Effects of MF on weight loss.

Average participant characteristics and anthropometrics at baseline and control day overall and in the groups are shown in Table 1a. The mean age of the overweight/obese participants was 37.7±8.3 years old, and the range of BMI laid between 25.1 and 42.58.

 

Table 1a.  Anthropometrics and characteristics of overweight/obese participants at baseline and control day, also in the groups of 2 types of meal frequency (FEO- Frequently Eating Overweight/obese; SEO- Seldom Eating Overweight/obese)

 

Baseline (Day 0) – BEFORE the diet

 

Control day (Day 29) – AFTER the diet

 

Overweight/

obese

FEO

SEO

 

Overweight/

obese

FEO

SEO

Number of participants

35

18

17

 

35

18

17

Gender

F

F

F

 

F

F

F

Age

37.7±8.3

39.9±9.5

35.4±6.3

 

37.7±8.3

39.9±9.5

35.4±6.3

Height, cm

164.1±7

162.4±7

165.8±6.7

 

164.1±7

162.4±7

165.8±6.7

Weight, kg

81.6±13.5

83.9±16.3

79.1±9.8

 

78.4±13.2

80.6±15.5

76.2±10.2

BMI

30.2±4

31.6±4.6

28.7±2.5

 

29±3.8

30.3±4.3

27.6±2.7

Waist circumference

90.4±9.6

92.4±11.3

88.1±6.9

 

86.8±9.8

88.8±11.7

84.7±6.9

Hips circumference

109.8±9.5

110.9±11.5

108.7±7.1

 

107±8.8

108.7±9

105±7.8

W/H ratio

0.83±0.09

0.84±0.1

0.81±0.08

 

0.81±0.08

0.8±0.09

0.81±0.08

Excess weight, kg

14.2±10.9

17.8±12.6

10.3±7.1

 

11±11.8

14.8±14.4

7±6.4

Mean Hunger

(from 3 meals)

5.2±1.9

4.7±1.9

5.6±1.9

 

4.5±2.2

4.5±1.7

4.4±2.6

Mean Satiety

(from 3 meals)

6.5±2.4

6.3±2

6.8±2.8

 

7.3±2

7.1±1.6

7.5±2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Study 2. Effect of MF on hunger and satiety. 

The 26 healthy-weight participants were aged between 27 and 44, and their mean BMI was 22.6 (SD=1.5). The anthropometric characteristics and Hunger/Satiety rates at Day0 (baseline) and Day29 (control day) are performed in Table 1b 

 

Table 1b.  Anthropometrics and characteristics of participants with healthy weight at baseline and control day, also in the groups of 2 types of meal frequency (FEH- Frequently Eating Healthy-weight; SEO- Seldom Eating Healthy-weight)

 

Baseline (Day 0) – BEFORE the diet

 

Control day (Day 29) – AFTER the diet

 

Healthy-weight

FEH

SEH

 

Healthy-weight

FEH

SEH

Number of participants

26

10

16

 

26

10

16

Gender

F

F

F

 

F

F

F

Age

35±5

34.6±5.4

35.3±5

 

35±5

34.6±5.4

35.3±5

Height, cm

167±5.8

168.4±6.8

166.2±5.2

 

167±5.8

168.4±6.8

166.2±5.2

Weight, kg

63.2±5.3

64.2±7.2

62.5±3.8

 

60.9±4.9

61.7±6.6

60.5±3.7

BMI

22.6±1.5

22.6±1.8

22.6±1.3

 

21.8±1.4

21.7±1.5

21.9±1.3

Waist circumference

75.5±6.6

77.4±7.1

74.4±6.3

 

72.6±6

73.8±5.6

71.9±6.2

Hips circumference

99±4.5

99.6±6.2

98.6±3.2

 

96.3±4.7

96.6±4.5

96.1±5

W/H ratio

0.76±0.06

0.78±0.07

0.75±0.06

 

0.75±0.06

0.77±0.06

0.75±0.07

Mean Hunger

(from 3 meals)

5.3±1.8

5±2

5.5±1.8

 

4.7±2.7

4.7±2.5

4.8±2.8

Mean Satiety

(from 3 meals)

7.2±1.3

7.6±1.2

7±1.2

 

8±1.4

8±1.5

7.9±1.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3.2 Weight loss in overweight/obese group after 28-day diet intervention (Study 1)

 

Following the 4-week intervention, the participants` body Excess Weight significantly decreased versus baseline for both FEO and SEO groups (FEO: t=3.56, DF=17, p=0.002, SEO: t=5.99, DF=16, p=0.001) (Figure 1). Similarly, the significant reduction happened in total body weight, waist, and hip circumferences (p=0.001-0.005) in both meal frequency groups of overweight/obese participants (Table 1a). However, due to the high dropout, the frequent eaters initially had more excess weight than seldom eaters did. This can appear to be a limitation of group equality.

Figure 1. Excess weight (kg) in mean on Day0 (baseline) and Day29 (control day) in both observed groups, frequent eaters (FEO), and seldom eaters (SEO), in Study 1 (in overweight/obese participants). The significant decrease can be seen in both groups (FEO p=0.002, SEO p=0.001).

 

 

3.3 Comparison of weight loss (in % of Body Mass) between Frequent Eaters and Seldom Eaters (Study 1)

Figure 2 depicts the difference between the percent of body weight being lost during the experiment in groups with different eating frequency. The mean weight loss (WL) in overweight/obese individuals who applied 4-5 meals a day was 3.84% (SD=2.39%) of body mass (BM), and 3.86% (SD=1.89%) of body mass in participants consumed 3-meal-diet. The difference in weight loss in % of BM between the groups was not significant (t=-0.025, DF=33, p=0.980) as well as between weight loss in percentage of Excess Body Weight (t=-1.431, DF=33, p=0.162). The detailed look at weight loss overall and in the groups can be taken in Table 2.

 

In addition, healthy-weight participants also reduced their body weight due to the adhering to the balanced diet, despite the given weight-maintaining but not weight-loss-purpose formula (see Table 2), but they remained within healthy BMI (18.5 to 24.9). And this weight loss, similarly to the overweight/obese group, did not differ between the Frequent Eaters and Seldom Eaters (t=1.145, DF=24, p=0.263).

Figure 2. The difference in Weight loss (in % of body mass) between FEO and SEO groups (frequently eating overweight/obese and seldom eating overweight/obese participants respectively).

  

 

Table 2.  Weight loss in participants after 28 days of diet-intervention (equal diet, split by 4-5 and 3 meals a day) in all groups of the experiment, where FEO-frequently eating overweight/obese, SEO-seldom eating overweight/obese, FEH- frequently eating healthy-weight, SEO-seldom eating healthy-weight participants.

 

All

Overweight

/obese

FEO

SEO

Healthy-weight

FEH

SEH

Number of participants

61

35

18

17

26

10

16

Weight loss, kg

2.75±1.5

3.15±1.66

3.31±1.98

2.98±1.27

2.23±1.08

2.57±1.3

2.01±0.88

Weight loss (% of
body mass, for all)

3.70±1.9

3.85±2.13

3.84±2.39

3.86±1.89

3.49±1.58

3.93±1.91

3.21±1.32

Weight loss

(% of excess weight,
for overweight/obese)

 

35.91±28.52

29.31±21.56

42.9±33.68

 

 

 

 


3.4 Changes in Hunger ratings over 28-day diet intervention in frequently eating and seldom eating healthy-weight participants (groups FEH and SEH respectively) (Study 2).

The Hunger rating throughout a day (i.e. mean hunger) also was counted from 3 values: hunger rating 10 minutes before Breakfast, hunger rating 10 minutes before Lunch, hunger rating 10 minutes before Dinner, according to the VAS (visual analog scales) outcomes on Day0 and Day29.

The decline in hunger ratings over the time of diet-intervention was identified as not significant in both Frequent (t=0.517, DF=9, p=0.618) and Seldom healthy-weight eaters (t=1.022, DF=15, p=0.323) (Figure 3). At baseline, an average hunger rating of participants in the FEH group was 5±2 whereas after 28 days of the 4-5-meals-a-day diet it appeared to be in mean 4.7±2.5.
Similarly, SEH-group individuals` hunger rating in the beginning (Day0) was 5.5±1.8, which declined to 4.8±2.8 on Day29. The total and in-groups hunger ratings in the beginning and at the end of the trial are shown in Table 1b.

In addition, in overweight/obese participants the hunger ratings similarly did not declined considerably in both groups FEO (t=0.413, DF=17, p=0.685) and SEO (t=1.497, DF=16, p=0.154) (Table 1a)

Figure 3. The mean Hunger in FEH (frequently eating healthy-weight individuals) and SEH (seldom eating healthy-weight individuals) on Day0 (baseline) and Day29 (control day).  The decline after 28-day diet intervention can be seen, but not significant (FEO p=0.618, SEO p=0.323)

 

3.5 Changes in Satiety ratings over 28-day diet intervention in frequently eating and seldom eating healthy-weight participants (groups FEH and SEH respectively) (Study 2).

The Satiety rating throughout a day (i.e. mean satiety) was estimated from 3 values: satiety 10 minutes after Breakfast, satiety 10 minutes after Lunch, satiety 10 minutes after Dinner, according to the VAS (visual analog scales) outcomes on Day0 and Day29.

On Day0 the participants from the group with frequent eating had a satiety rating 7.6 in mean (SD 1.2), which improved in 28 days of the diet but not significantly to 8±1.5 (t=-0.982, DF=9, p=0.352), whereas satiety ratings of seldom eaters significantly increased from 7±1.2 to 7.9±1.5 (t=-2.326, DF=15, p=0.034). The dynamics are illustrated in Figure 4. The total and in-groups satiety ratings in the beginning and at the end of the trial are shown in Table 1b.

 

Additionally, in overweight/obese subjects the satiety ratings similar to healthy-weight frequent eaters did not elevate remarkably in both groups FEO (t=-1.637, DF=17, p=0.120) and SEO (t=-0.866, DF=16, p=0.399) (Table 1a)

Figure 4. The mean Satiety in FEH (frequently eating healthy-weight individuals) and SEH (seldom eating healthy-weight individuals) on Day0 (baseline) and Day29
(control day).  The significant increase after 28-day diet intervention can be seen in SEO (p=0.034), but not in FEO (p=0.352).

 

3.6 Comparison Hunger and Satiety ratings on Day 29 in frequent and seldom eaters, and in all 4 groups (two groups with healthy-weight individuals and two groups with overweight/obese participants).

Whole sample

The appetite ratings did not significantly differ after 28 days of the diet intervention between all frequent eaters (from both healthy-weight and overweight/obese groups) and all seldom eaters. Independent t-test identified no significant difference in hunger: t=0.031, DF=59, p=0.976, as well as in satiety – t—0,671, DF=59, p=0,505.

The identical outcomes were detected in all four groups of participants. The mean hunger on Day29 and mean satiety on Day29 were similar in all four groups of participants (FEH, SEH, FEO, SEO) from both studies (ANOVA for hunger: F=0.076, DF=3, p=0.972; ANOVA for satiety: F=0.943, DF=3, p=0,426).

3.7 Diet compliance and physical activity.

Whole sample

 

The average diet compliance in all participants appeared to be 7.82±1.98 in mean according to VAS (visual analog scales), with negligible difference between frequent and seldom eaters (p=0.793). Besides, the recommended physical activity of 150 minutes a week was completed by 95.1% of participants.

 

 

4. Discussion

 

This pilot randomized controlled trial examined the effects of meal frequency, differing only by 1-2 meals, on weight loss, hunger, and satiety in women.

4.1 Hypothesis 1: Meal frequency and weight loss (Study 1).

We had postulated that consuming every 3-4 hours (i.e. 4-5 times a day) of higher in protein, moderately restricted in calories diet might help in a greater weight loss in overweight/obese individuals than eating the same diet but every 5-6 hours (i.e. 3 times a day). The present results do not support this hypothesis. Although the significant weight loss was observed in overweight/obese participants (3.15±1.66 kg or 36% of excess weight in mean) after 28-day of identical diet, no significant difference was detected between the groups of frequent and seldom eaters (p=0.980). Both frequent and seldom overweight/obese eaters lost a similar amount of body weight, 3.84% and 3.86% in mean respectively.

In our pilot trial, we applied higher in protein and moderately restricted in energy diet, similar to Anciero`s study in 2013, which detected a favorable effect of increased MF on weight loss. However, the mentioned trial compared 3 and 6 meals versus our 3 against 4-5 meals, which may be a more likely reason for the difference in the results. Furthermore, comparing to this trial, our study was carried out in online mode without the opportunity to estimate pure fat mass losses. This could be the strong limitation in our experiment since Anciero with colleagues identified identical total weight loss in kilograms in both groups of their participants, but with considerable difference in pure total and abdominal fat mass (Anciero et al., 2013).

Our findings appeared to agree with Cameron et al. (2010), who determined that increased MF (6 vs 3 meals) does not promote a greater body weight and body fat loss in obese adults during an equi-energetic energy-restricted diet. However, first of all, a large caloric deficit (700 kcal) was used in Cameron et al.`s study, which presumably could affect the lean mass losses (on average 2 kg in all participants), (Bopp et al., 2008). Second of all, the scientists designed a diet using a Guideline recommending 15-20% of protein intake, which perhaps was insufficient in the mentioned caloric restriction conditions, because differently from this, other studies showed a favorable retaining effect of higher MF on fat-free mass (Alencar et al.,2015). And consequently, sustaining lean mass may play an auspicious role in the weight loss process due to a greater resting metabolic body rate (Zurlo et al.,1990). All the mentioned points could affect the overall findings of the Cameron study. Although we can not estimate lean body mass change in the current experiment, this might be a useful point for further research.

 

4.2 Hypothesis 2: Meal frequency and hunger/satiety sensation (Study 2).

We had hypothesized, that eating more frequently (every 3-4 hours) may considerably improve appetite ratings in healthy-weight subjects, specifically, decrease hunger and increase satiety throughout a day, to a greater extent than consuming food rarely (every 5-6 hours). Hence, this could help in better weight management due to leading to overall energy intake reduction. The concept had been linked to other studies earlier that demonstrated a positive correlation between increased MF and better appetite regulation (Speechly et al., 1999; Smeets and Westerterp-Plantenga,2008; Bachman and Raynor, 2012; Anciero et al., 2013).

However, the present results do not support this hypothesis. No significant impact on both hunger and satiety ratings was found in frequent eaters over a 4-week diet intervention, whereas in contrast to our statement, lower MF (3 times a day) had a significant effect on satiety sensation in healthy weight participants (satiety rate increased by 0.77 in mean, p=0.034). Additionally, the hunger and satiety ratings appeared to be very similar in mean on the control day in all frequent and seldom eaters, including healthy-weight individuals from Study2 and overweight/obese subjects from Study1. Our findings agree with the trials, which found no added benefit of higher MF on hunger and satiety (Leidy and Campbell, 2011; Perrigue et al., 2016). Nevertheless, it is important to take into account, that the appetite sensations experience differently by various population groups (Gregersen et al.,2011), as well as depend on body composition (Frecka and Mattes,2008) and physical activity (King et al. 2012). Besides, self-reporting of the sensation of hunger and satiety, but not parallel appetite hormone assessment, particularly ghrelin, may strongly diminish the significance of our findings (Frecka and Mattes, 2008). Moreover, our finding that satiety rate significantly increased in seldom eaters could occur due to the diet composition, but not frequency (Leidy et al., 2011.)

 

4.3 Methodological strengths and limitations.

The strengths of the present pilot trial are performed as followed: precise monitoring of the diet adherence (daily control), studying both healthy-weight and overweight/obese individuals, applying identical physical activity conditions for all participants (95.1% feasibility), and using identical diets for studied groups of participants only split into different MF. However, some limitations took place in our study.  The first and main limitation is the impossibility to assess body composition, and consequently, assess pure fat mass and lean mass losses, as well as to measure appetite hormones such as ghrelin and leptin for detail hunger and satiety assessment. The second constriction is a relevantly small sample with only females observed. Thirdly, our study was not longitudinal enough to achieve robust changes in participants and see prospective weight maintenance. Lastly, the high participants withdrawing (particularly in the FEH group) may have led to the groups not being perfectly matched for BMI and excess weight, which is important.

 

 4.4 Conclusion

Overall, results from this study showed that eating more frequently (4-5 times a day) reduces body weight in the equivalent extent compared to seldom eating (3 times a day) in overweight/obese women under the conditions of identical, moderately restricted higher in protein diet, and 150 minutes of weekly physical activity. Furthermore, higher MF, similarly to lower MF, not significantly decreases hunger throughout a day in both healthy-weight and overweight/obese females. However, in contrast to our hypothesis, satiety sensation in healthy-weight participants appeared to be considerably increased after 28 days of seldom meal frequency, whereas in frequent eaters was slightly but not significantly improved in both healthy-weight and overweight/obese groups. In order to investigate the particular effects of meal frequency on weight loss and appetite ratings under similar to the present study conditions, future experimental research with precise body composition assessment and appetite hormones measuring is needed in a larger sample of both genders over a longer period.

 

 

 

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