Deprivation is an environmental experience that organisms are continually exposed to. However, few studies analyze deprivation effects on the consumption pattern during the post-deprivation period systematically. The aim of this study was to evaluate the deprivation effect on feeding pattern, growth rate and body weight during post-deprivation. Sixteen albino rats (3 months old at the beginning of the experiment) were exposed to 72-hour total food deprivation every 15 days. Food and water were freely available during non-deprivation periods. Rats completed three cycles comprised by a free access period followed by food deprivation. Once deprivation was removed, food and water consumption increased and then decreased, while body weight was recovered. Growth rate increased after every deprivation period and reached similar levels to those presented by the control group. Depriving rats from one commodity ( i.e., food) cause them to restrain their consumption of the other freely available commodity ( i.e ., water). Results confirm that food deprivation modifies growth rate, water and food consumption. Additionally, during post-deprivation period, differences between males and females were not registered.
When an organism is exposed to a water or food deprivation period, behavioral changes occur, affecting feeding patterns and body weight. Some of these changes include: a) feeding behavior adaptation to food availability periods [
Siegel [
With this previous evidence, the role of deprivation on eating behavior is undeniable, especially over food consumption. Nevertheless, a great percentage of studies have only focused on analyzing food consumption changes while applying different deprivation programs. During the post-deprivation or refeeding period, other modifications that we consider necessary to evaluate, like changes in growth rate, water consumption or behavioral differences between males and females occur. This last variable is of special interest since a great percentage of studies only use male rats. There are few studies that report deprivation effects on post-deprivation feeding pattern in females [
This experiment purpose was, therefore, to explore food restriction and refeeding cycles effects on subsequent feeding behavior, body weight and growth rate in female and male rats. From evidence, we hypothesized that animals exposed to food deprivation would be more likely to show subsequent disturbances in eating patterns and behavior; specifically binge eating, binge drinking, body weight recovery and growth rate increase. Water and food consumption was registered before, during and after deprivation. Also variations on body weight and growth rate were analyzed. Experimental conditions were designed to evaluate deprivation effects on body weight, food and water intake, growth rate and sexual differences during post-deprivation period.
Experimental subjects were 16 Winstar strain rats, 8 males (ME1, ME2, ME3, ME4, ME5 ME6, ME7, and M8) and 8 females (HE1, HE2, HE3, HE4, HE5, HE6, HE7, and HE8). Another 16 rats were control subjects (8 males: MC1, MC2, MC3, MC4, MC5, MC6, MC7, and MC8, and 8 females: HC1, HC2, HC3, HC4, HC5, HC6, HC7, and HC8). At the beginning of the experiment, female rats weighed 279 ± 14.7 g average and were 90 days old. Male rats weighed 413.85 ± 12.65 g (means ± SEM) and had the same age. Animals were singly housed in standard individual cages in an equipped room (21C +/− 2C) under a 12:12 light-dark cycle. All procedures in the present study were performed in accordance to the principles outlined by the Mexican Official Norm (NOM-062-ZOO-1999), Technical Specifications for the Production, Care and Use of Laboratory Animals.
All experimental operations were performed in individual home cages, constructed of Plexiglas (13 × 27 × 38 cm), with sawdust on the bottom, which was changed every 3 days. We used a precision electronic scale for body weight and food consumption measurements.
Standard Purina Roden Chow food for laboratory animals was used. Food consumption was registered in grams/ day and water consumption in ml/day.
Rats were divided in two groups, experimental and control, equated by body weight. Experimental group (males n = 8, females n = 8) initiated with a 15 days baseline period to determine body weight, food and water intake. Food was removed the following morning at 9 h during 72 hours to initiate the first deprivation period. Subjects returned to free access conditions during a 15 days period. This food deprivation-free access cycle was repeated until completing three cycles (periods 1, 2 and 3). The lasted free access period lasted 30 days. Control group (males n = 8, females n = 8) had free access to food and water during all the experiment. Food and water intake, and body weight were measured daily.
Data (food and water intake and body weight) was registered every day at 9 h in the morning, during 84 days. After data collection, we calculated means ± and standard error for body weight, food and water consumption, cumulative food intake and growth rate for both groups. Growth rate (Gr) was obtained as follows:
where fw represents the final weight and iw initial weight in a free access period; and t represents this period duration (in this case it was of 15 days). The last post-deprivation period was subdivided in two; from this subdivision periods 4 and 5 were obtained. A parametric contrast method, the Student’s t test was used to compare each group averages; since two independent groups of individuals were observed regarding a numerical variable under the assumptions of normality and equal variance. The graphics were created with Sigma Plot®.
During the first 15 days there was no significant difference in the animals baseline weights (
Within the first 15 days total food intake was not statistical different (
Similarly to total food consumption, total water consumption during the baseline did not have a sadistically significant difference (
Throughout the experiment, cumulative food consumption did not present significant differences.
During the first free access period, there was not statistically significant difference (
The relationship between body weight recovery and growth rate was an interesting finding. When body weight decreased during deprivation periods and recovering on the 2nd, 3rd, and 4th post-deprivation periods (free access) growth rate increased. However, during the 5th post-deprivation period, body weight recovery was related to a growth rate decrease (
Free access Periods | 1 Baseline | 2 Post-deprivation | 3 Post-deprivation | 4 Post-deprivation | 5 Post-deprivation | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Male | p | p | p | p | ||||||||||||
Control | Weight | 413.2 ± 13.1 g | 443 ± 12.4 g | 464.2 ± 11.4 g | 484.3 ± 11.9 g | 506.1 ± 11.1 g | ||||||||||
Experimental | Weight | 414.5 ± 12.6 g | ↓ 422 ± 12.6 g | <0.01 | ↓ 435 ± 12.3 g | <0.01 | ↓ 452 ± 12.2 g | <0.01 | ↑ 488 ± 13.1 g | |||||||
Experimental | Growth rate | 2 ± 0.14 g | ↑ 2.5 ± 0.2 g | <0.01 | ↑ 2.3 ± 0.07 g | <0.01 | ↑ 1.9 ± 0.10 g | <0.01 | ↓ 1.2 ± 0.11 g | <0.05 | ||||||
Control | Growth rate | 1.96 ± 0.16 g | 1.3 ± 0.1 g | 0.83 ± 0.09 g | 0.91 ± 0.08 g | 0.69 ± 0.1 g | ||||||||||
Female | ||||||||||||||||
Control | Weight | 279 ± 14.1 g | 286.7 ± 12.8g | 292.5 ± 12.3 g | 303.3 ± 12.2 g | 307.3 ± 12.7 g | ||||||||||
Experimental | Weight | 279.4 ± 15.1g | ↓ 279 ± 14.1 g | <0.01 | ↓ 283 ± 14.4 g | <0.01 | ↓ 290 ± 14.5 g | <0.01 | ↑ 303 ± 14.1 g | |||||||
Experimental | Growth rate | 0.88 ± 0.05 g | ↑ 1.5 ± 0.06 g | <0.01 | ↑ 1.4 ± 0.10 g | <0.01 | ↑ 1.2 ± 0.06 g | <0.01 | 0.3 ± 0.04 g | |||||||
Control | Growth rate | 0.86 ± 0.05 g | 0.6 ± 0.06 g | 0.5 ± 0.04 g | 0.6 ± 0.06 g | 0.2 ± 0.07 g | ||||||||||
Results show an analysis of the data on post-deprivation periods. Means ± SEM of body weight and growth rate of experimental versus control groups was compared. Arrows indicate the relation between body weight and growth rate of experimental subjects.
Findings clearly show that food deprivation causes important changes during post-deprivation period in males as much as in females. Post deprivation periods changes were, body weight recovery, binge eating, binge drinking related to self-imposed deprivation, and a growth rate increase. Post-deprivation changes were observed in both inter- and intra-subjects statistical analyses.
Previous weight regulation and compensatory growth studies have used models which expose animals to food deprivation programs. These studies outcomes have not taken post-deprivation growth rate increase into consideration [
The present experiment results support the findings of previous studies showing that deprivation increases food intake during post-deprivation periods [
Polydipsia is a stereotyped pattern of drinking that can be caused by a variety of pathological or experimental factors [
These results suggest that, the deprivation program had the same effect in females and males, that is to say, no differences were observed in the body weight recovery, binge eating or binge drinking. Sefcikova and Mozes [
Binge eating and binge drinking inadequate operational characterization was a limitation for this study. Scientific evidence has identified these two types of behavior, from an increase of food and water consumption compared to baseline [
It seems reasonable to conclude that food deprivation modifies multiple factors during the post-deprivation period. These changes are called post-deprivation effects. Binge eating and binge drinking are related to deprivation and its nature seems to be regulatory due to the fact that it disappears when deprivation is retired. Body weight recovery is related to growth rate. Further work is necessary to clarify which factors influence growth rate, and to explore deprivation intensity variations and their effects on binge eating, binge drinking and self- imposed deprivation.
The research is financed by CONACYT project-CB 156821.
AntonioLópez-Espinoza,Alma Gabriela MartínezMoreno,Virginia Gabriela AguileraCervantes,Elia ValdésMiramontes,Luis Alfonso MojicaContreras,MonicaNavarro-Meza,Claudia PatriciaBeltrán-Miranda,Ana CristinaEspinoza-Gallardo, (2015) Feeding Behavior, Body Weight and Growth Rate during Post-Deprivation Period in Rats. Food and Nutrition Sciences,06,1307-1315. doi: 10.4236/fns.2015.614136