Diet and exercise in obese subjects: self-report versus controlled measurements

Cancer patients participating in a lifestyle intervention during chemotherapy greatly over-report their physical activity level: a validation study

BACKGROUND

The short form of the International Physical Activity Questionnaire (IPAQ-sf) is a validated questionnaire used to assess physical activity (PA) in healthy adults and commonly used in both apparently healthy adults and cancer patients. However, the IPAQ-sf has not been previously validated in cancer patients undergoing oncologic treatment. The objective of the present study was to compare IPAQ-sf with objective measures of physical activity (PA) in cancer patients undergoing chemotherapy.

METHODS

The present study was part of a 12-month prospective individualized lifestyle intervention focusing on diet, PA, stress management and smoking cessation in 100 cancer patients undergoing chemotherapy. During the first two months of the lifestyle intervention, participants were wearing an activity monitor (SenseWear™ Armband (SWA)) for five consecutive days while receiving chemotherapy before completing the IPAQ-sf. From SWA, Moderate-to-Vigorous intensity PA (MVPA) in bouts ≥10 min was compared with self-reported MVPA from the IPAQ-sf. Analyses both included and excluded walking in MVPA from the IPAQ-sf. Results were extrapolated to a wearing time of seven days.

RESULTS

Sixty-six patients completed IPAQ-sf and wore the SWA over five days. Mean difference and limit of agreement between the IPAQ-sf and SWA including walking was 662 (±1719) min(.)wk(-1). When analyzing time spent in the different intensity levels separately, IPAQ-sf reported significantly higher levels of moderate (602 min(.)wk(-1), p = 0.001) and vigorous (60 min(.)wk(-1), p = 0.001) PA compared to SWA.

CONCLUSIONS

Cancer patients participating in a lifestyle intervention during chemotherapy reported 366 % higher MVPA level from the past seven days using IPAQ-sf compared to objective measures. The IPAQ-sf appears insufficient when assessing PA level in cancer patients undergoing oncologic treatment. Activity monitors or other objective tools should alternatively be considered, when assessing PA in this population.

Patterns of objectively measured physical activity in normal weight, overweight, and obese individuals (20-85 years): a cross-sectional study

BACKGROUND

The magnitude of the association between physical activity (PA) and obesity has been difficult to establish using questionnaires. The aim of the study was to evaluate patterns of PA across BMI-defined weight categories and to examine the independent contribution of PA on weight status, using accelerometers.

METHODS

The study was a cross-sectional population-based study of 3,867 adults and older people aged 20-85 years, living in Norway. PA was assessed for seven consecutive days using the ActiGraph GT1M accelerometer. Anthropometrical data was self-reported and overweight and obesity was defined as having a body mass index (BMI) of 25-<30 and ≥30 kg/m(2), respectively.

RESULTS

Overweight and obese participants performed less overall PA and PA of at least moderate intensity and took fewer steps, compared to normal weight participants. Although overall PA did not differ between weekdays and weekends, an interaction between BMI category and type of day was present, indicating a larger difference in overall PA between BMI categories on weekends compared to weekdays. Obese participants displayed 19% and 25% lower overall physical activity compared to normal weight participants, on weekdays and weekends, respectively. Participants in the most active quintile of overall PA had a 53% lower risk (OR 0.47, 95% CI: 0.37 to 0.60) for having a BMI above or below 25 kg/m(2), and a 71% lower risk (OR: 0.29, 95% CI: 0.20 to 0.44) for having a BMI above or below 30 kg/m(2).

CONCLUSIONS

Overweight and obese participants engaged in less overall PA and moderate and vigorous PA compared with normal weight individuals. The weight related differences in overall PA were most pronounced on the weekend and the risk of being overweight or obese decreases across quintiles of PA.

Moderate-to-vigorous physical activity and sedentary behaviours in relation to body mass index-defined and waist circumference-defined obesity

The aim of the present study was to investigate the relationships of physical activity types and sedentary behaviour with BMI and waist circumference (WC). The sample comprised 6215 adults (2775 men, 3440 women) aged 16 years and over living in Scotland. Self-reported physical activity of moderate to vigorous intensity (MVIA) included domestic activity, walking, and sports and exercises. MVIA levels were classified as being inactive, being insufficiently active, being sufficiently active for general health benefits and being sufficiently active for obesity prevention. Sedentary time was defined as television and other screen-based entertainment time (TVSE). Dependent variables were BMI-defined obesity (BMI-OB) and WC-defined obesity (WC-OB). TVSE was positively related to both WC-OB (adjusted OR 1.69 (95 % CI 1.39, 2.05) for > or = 4 h of TVSE per d compared with < 2 h/d) and BMI-OB (OR 1.88; 95 % CI 1.51, 2.35) independently of MVIA. Those classified as most active who reported > or = 4 h/d of TVSE had higher prevalence of BMI-OB (18.9 v. 8.3 %; P < 0.05) and WC-OB (28.0 v. 10.0 %; P < 0.01) than those equally active with < 2 h/d of TVSE. Sports and walking were related inversely to WC-OB (OR for no time compared with > or = 30 min/d: 1.55 (95 % CI 1.24, 1.94); 2.06 (95 % CI 1.64, 2.58)), but only walking was related to BMI-OB (OR 1.94; 95 % CI 1.58, 2.37). Domestic physical activity was not related to BMI-OB or WC-OB. In conclusion, physical activity and sedentary behaviour are independently related to obesity. Public health recommendations should both promote physical activity and discourage engagement in sedentary pursuits.

Association between walking distance and percentiles of body mass index in older and younger men

OBJECTIVE

To assess the association of weekly walking distance to body weight and waist circumference in elderly (age > or =75 years), senior (55< or = age <75 years), middle-aged (35< or = age <55 years), and younger men (18< or = age <35 years old).

DESIGN

Cross-sectional analyses of baseline questionnaires from 7082 male participants of the National Walkers' Health Study.

RESULTS

Standard regression analyses showed that body mass index (BMI) was inversely and significantly associated with walking distance (kg/m(2) per km/week) in elderly (slope (SE): -0.032 (0.008)), senior (-0.045 (0.005)) and middle-aged men (-0.037 (0.007)), as were their waist circumferences (-0.090 (0.025), -0.122 (0.012) and -0.091 (0.015) cm per km/week, respectively), and that these slopes remained significant when adjusted statistically for reported weekly servings of meat, fish, fruit and alcohol. However, percentile regression analyses showed that the declines in BMI per km/week walked were greater at the higher than the lower percentiles of the BMI distribution. In men > or =74 years old the decline per km walked was 4.9-fold greater among the heaviest men (that is, 90th BMI percentile; -0.076 kg/m(2) per km/week) than among the leanest men (that is, 10th BMI percentile; -0.015 kg/m(2) per km/week). The differences in slope at the 90th compared to the 10th BMI percentile were 5.4-fold among men 55-74 years old and sixfold among men 35-54 years old. Per km/week walked, the declines at the 90th percentile of waist circumference were also greater than at its 10th percentile, and intermediate for percentiles in between. Whereas standard regression analyses suggest that the average declines in BMI per km/week walked reported here are consistent with those reported previously per km/week run in male runners 35-54 years old (-0.036 (0.001) kg/m(2) per km/week) and > or =50 years old (-0.038 (0.001) kg/m(2) per km/week), percentile regression analyses showed that when adjusted to the leaner body weights of the runners the declines per km walked were between 49% and 59% less for walkers than runners.

CONCLUSIONS

Declines in BMI and waist circumferences with walking distance depend upon the percentile of the BMI distribution, with the decline per km walked being significantly greater among heavier men.

The role of diet and exercise for the maintenance of fat-free mass and resting metabolic rate during weight loss

The incidence of obesity is increasing rapidly. Research efforts for effective treatment strategies still focus on diet and exercise programmes, the individual components of which have been investigated in intervention trials in order to determine the most effective recommendations for sustained changes in bodyweight. The foremost objective of a weight-loss trial has to be the reduction in body fat leading to a decrease in risk factors for metabolic syndrome. However, a concomitant decline in lean tissue can frequently be observed. Given that fat-free mass (FFM) represents a key determinant of the magnitude of resting metabolic rate (RMR), it follows that a decrease in lean tissue could hinder the progress of weight loss. Therefore, with respect to long-term effectiveness of weight-loss programmes, the loss of fat mass while maintaining FFM and RMR seems desirable. Diet intervention studies suggest spontaneous losses in bodyweight following low-fat diets, and current data on a reduction of the carbohydrate-to-protein ratio of the diet show promising outcomes. Exercise training is associated with an increase in energy expenditure, thus promoting changes in body composition and bodyweight while keeping dietary intake constant. The advantages of strength training may have greater implications than initially proposed with respect to decreasing percentage body fat and sustaining FFM. Research to date suggests that the addition of exercise programmes to dietary restriction can promote more favourable changes in body composition than diet or physical activity on its own. Moreover, recent research indicates that the macronutrient content of the energy-restricted diet may influence body compositional alterations following exercise regimens. Protein emerges as an important factor for the maintenance of or increase in FFM induced by exercise training. Changes in RMR can only partly be accounted for by alterations in respiring tissues, and other yet-undefined mechanisms have to be explored. These outcomes provide the scientific rationale to justify further randomised intervention trials on the synergies between diet and exercise approaches to yield favourable modifications in body composition.

BMI change and leisure time physical activity (LTPA): an 11-y follow-up study in apparently healthy men aged 20–69 y with normal weight at baseline

OBJECTIVE

To study the association between self-reported leisure time physical activity (LTPA) at baseline and change in body mass index (BMI).

DESIGN

Prospective observational study with a 11-y follow-up period.

SETTING

A total population-based health survey in one county was performed in 1984-1986 (HUNT 1) and repeated in 1995-1997 (HUNT 2).

PARTICIPANTS

In total, 21 685 men participated in both surveys. In the present study, we included only apparently healthy 20-69-y-old men participating in both surveys and who had a normal body weight (BMI 18.5-24.9 kg/m(2)) at baseline-leaving 8305 men for the analyses. In all, 6945 men answered all questions about LTPA and 6749 men had complete data in the multiple analyses.

MEASUREMENTS AND MAIN RESULTS

At HUNT 1, the participants answered questions (self-reported) about the intensity, frequency and duration of LTPA. The association between change in BMI and LTPA was investigated in multiple linear regression analyses. Adjusted for smoking, education, age and BMI at baseline, the physical active cohort gained less weight than the inactive cohort. Low, moderate and high levels of LTPA showed a U-shaped effect adjusted for smoking, education, age and BMI at baseline. Adjusted for BMI and age at baseline, the high-intensity part of the physically active cohort gained less weight than the low-intensity group.

CONCLUSION

This study has demonstrated a moderate BMI effect of LTPA at the population level; however, even a high level of LTPA did not prevent weight gain during the 11-y follow-up period.

Leisure Time Physical Activity and Change in Body Mass Index: An 11-Year Follow-Up Study of 9357 Normal Weight Healthy Women 20–49 Years Old

OBJECTIVE

To study the association between self-reported leisure time physical activity at baseline (1984-1986) and change in body mass index (BMI) during an 11-year follow-up period (1995-1997). The study population was 9357 healthy women, aged 20-49 years, who had a normal body weight (BMI 18.5-24.9 kg/m2) at baseline.

METHODS

A general population-based health survey was performed both in 1984-1986 (HUNT 1) and 1995-1997 (HUNT 2). Leisure time physical activity at HUNT 1 was categorized into high, moderate, and low levels based on self-reported intensity, duration, and frequency. Women who at baseline reported diabetes, stroke, angina, myocardial infarction, or long-term illnesses impairing their activities of living were excluded.

RESULTS

Physical activity was a significant predictor of BMI at HUNT 2 adjusted for BMI,age, and education at HUNT 1. Low level of leisure time physical activity compared with high level at baseline was significantly associated with a higher BMI 11 years later. Those with high level of activity gained 0.18 kg/m2 (95% CI 0.05, 0.32) less than those with low level of physical activity over 11 years.

CONCLUSIONS

This study has demonstrated that leisure time physical activity has a moderate effect on BMI. However, not even a high level of leisure time physical activity was sufficient to prevent weight gain and BMI increase in all subgroups of the study population.

Time course for changes in aerobic capacity and body composition in overweight men and women in response to long-term exercise: the Midwest Exercise Trial (MET)

OBJECTIVE

To determine the time course for changes in aerobic capacity, body weight (BW), and composition in overweight adults in response to a supervised exercise trial with a targeted energy expenditure of 2000 kcal week(-1).

DESIGN

The Midwest Exercise Trial (MET) was a randomized, controlled, 16-month verified, supervised exercise trial. Aerobic exercise progressed to 45 min day(-1), 5 days week(-1) over 6-months and was then maintained for 10 months. Controls maintained their normal physical activity and all participants maintained ad libitum diets.

SUBJECTS

A total of 131 participants were randomized to exercise or control groups and 74 completed the intervention and all laboratory testing.

MEASUREMENTS

At baseline and months 4, 9, 12, and 16, aerobic capacity (VO(2max) ) was measured by indirect calorimetry, BW by digital scale, and fat weight and fat-free weight by hydrostatic weighing.

RESULTS

Aerobic capacity (ml kg(-1) min(-1)) increased (P<0.05) from baseline (39.2+/-5.2, mean+/-s.d.) to 9 months (48.8+/-4.3) in exercising men as well as women (32.8+/-4.2-39.6+/-5.5) with no significant changes occurring at 12 or 16 months. From baseline to 9 months BW (94.0+/-12.6-88.7+/-9.7 kg) and fat weight (26.8+/-6.8-21.8+/-4.5 kg) significantly decreased in exercising men with no changes occurring at 12 or 16 months. There were no changes in fat-free weight across the 16 months for exercising men or for BW or composition in exercising women. Further, there were no significant changes for the control men for aerobic capacity, BW, or body composition across 16 months. Women in the control group showed significant increases in weight of 2.9+/-5.5 kg and fat weight of 2.1+/-4.8 kg at 16 months only.

CONCLUSIONS

We recommend that investigations that use exercise without diet as the stimulus for weight loss have at least a 9-month duration to provide sufficient time for the full effects to be realized, should such effects be present.

Physical fitness and physical activity in obese and nonobese Flemish youth

OBJECTIVE

To assess different aspects of physical fitness and physical activity in obese and nonobese Flemish youth.

RESEARCH METHODS AND PROCEDURES

A random sample of 3214 Flemish schoolchildren was selected and divided into an "obese" and "nonobese" group based on body mass index and sum of skinfolds. Physical fitness was assessed by the European physical fitness test battery. Physical activity was estimated by a modified version of the Baecke Questionnaire.

RESULTS

Obese subjects had inferior performances on all tests requiring propulsion or lifting of the body mass (standing-broad jump, sit-ups, bent-arm hang, speed shuttle run, and endurance shuttle run) compared with their nonobese counterparts (p < 0.001). In contrast, the obese subjects showed greater strength on handgrip (p < 0.001). Both groups had similar levels of leisure-time physical activity; however, nonobese boys had a higher sport index than their obese counterparts (p < 0.05).

DISCUSSION

Results of this study show that obese subjects had poorer performances on weight-bearing tasks, but did not have lower scores on all fitness components. To encourage adherence to physical activity in obese youth, it is important that activities are tailored to their capabilities. Results suggest that weight-bearing activities should be limited at the start of an intervention with obese participants and alternative activities that rely more on static strength used.

Temporal trends in energy intake in the United States: an ecologic perspective

BACKGROUND

The causes of recent increases in the prevalence of overweight in the United States are perplexing because national survey data do not show clear patterns of change in energy intake or expenditure.

OBJECTIVE

Ecologic data regarding the quantities and types of foods and nutrients available in the United States between 1970 and 1998 were reviewed to provide an alternative perspective on trends in energy intake.

DESIGN

Literature searches in agriculture, business, and medical library databases were conducted to identify data regarding the quantities and types of foods and nutrients available in the United States between 1970 and 1998.

RESULTS

Per capita energy availability estimates from the US Department of Agriculture, US Food Supply Series, indicate that energy availability increased by 15% between 1970 and 1994. Data regarding trends in food purchasing and preparation suggest that Americans are eating more meals outside the home, relying more heavily on convenience foods, and consuming larger food portions. Americans appear, in some cases, to be selecting lower-fat foods over higher-fat alternatives. In addition, availability and sales of reduced-energy and reduced-fat products have increased.

CONCLUSION

Consistent with trends in overweight, most of the ecologic data reviewed suggest that energy intake has increased over the past several decades and is likely a major contributor to increases in average body weight.

Potential underreporting of energy intake in the Ontario Health Survey and its relationship with nutrient and food intakes

This study investigated potential underreporting of energy intake in the 1990 Ontario Health Survey (OHS). Underreporting was higher in overweight individuals, Asian-born individuals, and respondents from urban areas. Intakes of underreporters were slightly closer to current dietary guidelines (less fat, more fruit and vegetables, fewer sweets). These results underline that caution is warranted when interpreting the association of dietary data with health outcomes.

Impact of adopting lower-fat food choices on nutrient intake of American children

OBJECTIVE

To compare the overall nutrient intake of American children (ages 2 to 19) who exclusively use skim milk instead of 1%, 2%, or whole milk; lean meats instead of higher-fat meats; or fat-modified products instead of full-fat products.

STUDY DESIGN

A unique sorting procedure was used to categorize respondents to the 1989-1991 Continuing Survey of Food Intake by Individuals according to reported use or nonuse of certain fat-reduction strategies. Differences in intake of 23 macronutrients and micronutrients, as well as energy, by exclusive users, mixed users, and nonusers of each strategy were statistically analyzed using analysis of variance with Scheffe's test. The number of fat-reduction strategies used by the children as well as demographic characteristics also were analyzed.

RESULTS

Only a small number of children qualified as exclusive users of skim milk (3%), lean meats (2%), and fat-modified products (1%). Energy intakes for all children were below 100% of the recommended dietary allowance. However, children (n = 85) who used skim milk exclusively in place of higher-fat milks closely approximated the current dietary recommendations (30% energy from fat, less than 10% from saturated fat, and less than 300 mg cholesterol) while maintaining adequate micronutrient intake and without significantly impacting energy. Children (n = 52) who used lean meats in place of higher-fat meats achieved the guideline for total fat; however, energy intake was 70% of the recommended dietary allowance and vitamin E was 63%. Children (n = 20) who use only fat-modified versions of cheese, salad dressing, cake, pudding, and yogurt made no significant impact on their energy, fat, or micronutrient intake. Of the 3299 children in the data set, only 3 qualified as users of two fat-reduction strategies and none qualified as users of all three strategies. Exclusive users of skim milk, lean meat, or fat-modified products were more likely to be female, white, and live in families with higher incomes. Those using skim milk or lean meat exclusively also were more likely to be older, whereas those exclusively using fat-modified products were younger. Furthermore, those using skim milk or fat-modified products exclusively were more likely to live in households where the head had more years of education, whereas those exclusively using lean meats were from households headed by those with slightly less years of education.

CONCLUSIONS

Despite the inherent limitations of population-based food surveys (including issues of underreporting, lack of biological markers and accurate anthropometric measures, and limited nutrient databases), these results provide insight into the rate of use of certain lower-fat food choices by children and suggest exclusive use can facilitate achievement of contemporary dietary recommendations. The impact of using these fat-reduction strategies on children's overall nutrient intake differs depending on the strategy used. Use of skim milk is an economical single-food strategy that facilitates achievement of contemporary dietary guidelines while maintaining nutrient adequacy. Professional guidance is recommended for children who exclusively use lean meats to assure adequate intake of energy and vitamin E. The impact of fat-modified products needs to be monitored closely as the number of such products increases in the marketplace. Results of this study can be used by health professionals working with children and their parents to highlight the overall efficacy of dietary recommendations while alerting them to potential pitfalls.