The Association of Body Weight,Dietary Intake,and Energy Expenditure with Dietary Restraint and Disinhibition

LAWSON, OLGA J, DONALD A WILLIAMSON, CATHERINE M CHAMPAGNE, JAMES P DELANY, ELLEN R BROOKS, PAULA M HOWAT, PATRICIA J WOZNIAK, GEORGE A BRAY AND DONNA H RYAN. The association of body weight, dietary intake, and energy expenditure with dietary restraint and disinhibition. Obes Res. 1995;3:153–161. The hypotheses that dieting and/or overeating are associated with adiposity, eating disturbances, and lowered energy expenditure were tested in this study. A sample of 44 premenopausal women scoring high and low on measures of dietary restraint and disinhibition of dietary control, as measured by the Three Factor Eating Questionnaire, was studied. A 2 × 2 factorial design was employed (High/Low Restraint x High/Low Disinhibition). Dependent variables were: body composition, dietary intake, activity, resting metabolic rate, and thermic effect of food. Unrestrained overeaters (Low Restraint/High Disinhibition group) were very obese. High Dietary Restraint was associated with intent to diet and controlled eating. High scores on the Disinhibition Scale were associated with episodic overeating. Groups did not differ in resting metabolic rate (controlled for fat-free mass). Lower thermic effect of food was found to be associated with the obesity found in High Disinhibition subjects. Thus, Dietary Restraint was not associated with significant adverse effects upon physical or psychological health. High Disinhibition, however, was associated with adiposity and significant disturbances of eating.     

Gene or Size: Metabolic Rate and Body Temperature in Obese Growth Hormone‐Deficient Dwarf Mice

Objective: SMA1 mice carry a missense mutation in the growth hormone gene that leads to semidominant dwarfism and obesity. In this study, the basic thermal and metabolic properties of SMA1 mice were examined to detect metabolic alterations that can support the accretion of excess fat. Research Methods and Procedures: Basal and resting metabolic rates (RMRs) in wild‐type and SMA1 (sma1/+ and sma1/sma1) mice were determined by indirect calorimetry. Body temperature (T_b) was recorded using intraperitoneally implanted temperature‐sensitive transmitters, and body composition was determined by DXA. Results: SMA1 mice have proportionally lower basal and resting metabolic rates, higher body mass (BM)‐specific RMRs, and a higher lower critical temperature, and display a decrease in T_b by 0.4 °C in sma1/+ and 0.9 °C in sma1/sma1. Discussion: The analysis of gene effects on BM and energy expenditure in mouse mutants must consider the appropriate allometric relationship between BM and metabolic rate. With the exception of T_b, all metabolic alterations observed in SMA1 reflect reduced size.     

Birth Weight,Adult Body Composition,and Subcutaneous Fat Distribution

Objectives: To investigate if birth weight is related to both body mass index (BMI) and distribution of subcutaneous fat at adult age. Research Methods and Procedures: A 9‐year longitudinal study was performed in 229 subjects (192 women) with ages ranging from 27 to 36 years. Birth weight was retrieved by a questionnaire, and adult weight, height, skinfold thicknesses, and waist‐to‐hip ratio (WHR) were repeatedly measured at mean ages 27, 29, 31, and 36 years. BMI, sum of four skinfolds (S4S), the ratio between two truncal skinfolds and S4S (SS/S4S), and the ratio between WHR and the cross‐sectional area of the left thigh were calculated with the available data. Results: The adjusted model showed that in women, birth weight was significantly negatively related to adult S4S [β = ?5.211; (?9.768 to ?0.654)], waist circumference [β = ?1.449; (?2.829 to ?0.069)], and SS/S4S ratio [β = ?3.579; (?5.296 to ?1.862)]. In men, a significant negative association was observed between birth weight and adult WHR [β = ?1.096; (?2.092 to ?0.100)] only. Other relationships showed, although not significantly, the same negative trend, namely that lower birth weight is related to higher adult body fat mass (S4S) and a more truncal subcutaneous fat distribution (SS/S4S). No associations were found between birth weight and either adult BMI or the cross‐sectional area of the thigh. Discussion: Lower birth weight is, in both adult men and women, related to a higher adult subcutaneous fat mass and a more truncal distribution of subcutaneous fat, indicating a higher risk for obesity.     

Predictors of Long‐term Weight Maintenance

Objective: The purpose of this study was to evaluate available variables of a long‐term weight maintenance study to investigate possible factors predisposing to weight regain after a period of weight loss. Research Methods and Procedures: The Maastricht Weight Maintenance Study is an ongoing longitudinal study of healthy men and women (29 men and 62 women; 18 to 65 years of age; BMI = 30.2 ± 3.1 kg/m²). A variety of parameters were measured before and after a very‐low‐energy diet and after a follow‐up of at least 2 years. Results: Mean weight loss was 7.9 ± 3.6 kg, and percent weight regain was 113.8 ± 98.1%. Percent BMI regain was negatively associated with an increase in dietary restraint (r = ?0.47, p < 0.05). Percent weight regain was negatively correlated with baseline resting metabolic rate (r = ?0.38, p = 0.01) and baseline fat mass (r = ?0.24, p = 0.05) and positively correlated with the magnitude of change in body weight (BW) expressed as maximum amplitude of BW (r = 0.21, p < 0.05). In addition, amplitude of BW was positively correlated with the frequency of dieting (r = 0.57, p < 0.01). Discussion: The best predictors for weight maintenance after weight loss were an increase in dietary restraint during weight loss, a high baseline resting metabolic rate, a relatively high baseline fat mass favoring a fat‐free mass–sparing effect during weight loss, a rather stable BW, and a low frequency of dieting. Therefore, BW maintenance after BW loss seems to be a multifactorial issue, including mechanisms that regulate an individuals’ energy expenditure, body composition, and eating behavior in such a way that energy homeostasis is maintained.     

Effects of Sibutramine on Resting Metabolic Rate and Weight Loss in Overweight Women

Sibutramine, a monoamine re-uptake inhibitor, has recently been approved by the Food and Drug Administration as a weight loss agent. Sibutramine lowers body-weight in rodents by reducing energy intake and increasing energy expenditure. Sibutramine facilitates weight loss in human subjects, but it is not clear whether it acts on energy intake, energy expenditure, or both. The present study was a randomized clinical trial designed to assess the effects of sibutramine (at 10 or 30 mg/day) on body weight and resting metabolic rate (RMR). Forty-four overweight women were randomized to 1) placebo (n=15); 2) sibutramine at 10 mg/day (n=15) or, 3) sibutramine at 30 mg/day (n=14). All subjects were instructed to consume a 1200 kcal/day diet for 8 weeks while receiving drug or placebo. RMR was assessed by indirect calorimetry at baseline, at 3 hours after the first dose of drug (or placebo), and at the end of the 8-week weight-loss period. Sibutramine reduced body weight-relative to placebo, but there was no difference between weight loss on the two sibutramine doses. No significant differences in RMR between sibutramine and placebo were seen, either 3-hour post dose or after the 8-week weight-loss period. After the weight loss period, all groups were taken off medication and kept weight stable for another 4 weeks. RMR was measured again and was not different among groups. That there was no change in RMR when sibutramine was stopped further suggests that the drug does not directly affect RMR. In summary, while sibutramine was shown to be an effective weightloss agent over 8 weeks, we found no evidence that it increased RMR.     

Variation in Chemical Composition,Reproductive Success and Body Weight of Daphnia magna in Relation to Diet

The concern of this study has been the chemical composition of Daphnia magna, the algae (Selenastrum capricornutum, Ankistrodesmus convolutus) it was fed, the two growth media in which the algae were cultured and the water (Lake Huron, Michigan, USA) in which D. magna was reared. A synthetic diet (fish chow + alfalfa) was used as a control. The effectiveness of these five diets on the health of the D. magna populations was ascertained by the weight and number of neonates thus produced. The diet, S. capricornutum cultured in an organic medium, produced the largest mean brood size and the heaviest neonates in unstressed populations. The synthetic diet produced the smallest mean brood size and the lightest neonates. Stressed organisms may produce smaller broods with heavier neonates than unstressed organisms. The evolutionary significance of this observation is discussed. Statistical studies suggest that daphnids maintained on the synthetic diet derived no demonstrable nutritive value from the diet in terms of elemental composition or amino acid production. A great similarity in patterns of amino acid quantity and type was noted in the algae and the daphnids. On further examination it was discovered that this pattern was widespread in other aquatic forms, bacteria, fungi, yeasts, casein and was common to a variety of birds and mammals. It may be suggested that products that are made and stored, such as lipids, are less uniform in pattern among widely diverse species than those that have to be produced and are not stored, such as amino acids.     

Effects of Energy Expenditure and Ucp1 on Photoperiod‐Induced Weight Gain in Collared Lemmings

Objective: To determine the role of total energy expenditure (TEE) and its components in the ability of collared lemmings to increase weight in response to a decrease in photoperiod. Research Methods and Procedures: Energy expenditure was measured by 24‐hour indirect calorimetry concurrent with food‐intake studies. TEE and resting and nonresting energy expenditure (REE and NREE, respectively) were adjusted for body weight by analysis of covariance (ANCOVA). Uncoupling protein 1 (Ucp1) mRNA levels from interscapular brown adipose tissue were determined by Northern blot. Results: TEE and REE of lemmings exposed to a short photoperiod for 10 days were significantly lower than that of lemmings exposed to a long photoperiod (p < 0.05), whereas NREE was not significantly different (p = 0.44). Ucp1 mRNA levels in interscapular brown adipose tissue were 50% lower in short‐ vs. long‐photoperiod lemmings (p < 0.01). Ucp1 mRNA levels were positively related to REE (r² = 0.79, p < 0.01). After adjustment of REE for differences in Ucp1 mRNA levels, there was no longer a significant difference attributable to photoperiod treatment (p = 0.54). Discussion: The results of this study indicate that the increase in body mass that occurs when collared lemmings are exposed to a short photoperiod may be primarily fueled by a decrease in REE and is correlated with a decrease in Ucp1 mRNA levels.     

A study on verifying the effectiveness of 4-week composite weight-loss dietary supplement ingestion on body composition and blood lipid changes in middle-aged women

Purpose

The purpose of this study was to investigate the effectiveness of a composite weight-loss dietary supplement on body composition and blood lipid changes in middle-aged women.

Methods

Thirty seven middle-aged women living in the Kyunggi area participated in this study and they were randomly divided into 2 groups (Dietary supplement ingestion group; DG, n = 20 and Placebo group; PG, n = 17). Blood draw and dual energy x-ray (DEXA) measurements were conducted to examine changes in body composition and blood lipids.

Results

There were no significant changes in weight and BMI in both groups. There was an interaction between the composite weight-loss dietary supplement intake and lean body mass in DG and there was a significant decrease in percent body fat in DG. Blood lipid changes in the study results showed that there was no significant difference in TC, TG, and LDL in both groups; however, there was a significant interaction between the composite weight-loss dietary supplement intake and HDL-C as well as an increase in the HDL-C of DG.

Conclusion

In conclusion, it seems that 4-week ingestion of the composite weight-loss dietary supplement decreased body fat, increased lean body mass, and increased HDL-C. Therefore, the composite weight-loss dietary supplement is expected to prevent obesity and induce health improvements in middle-aged women.     

力竭运动锻炼和饥饿对南方鲇静止代谢率及体重的影响

在25℃饥饿和维持日粮(1.5%体重)条件下,测定了连续15d无氧运动锻炼(追赶至力竭)及随后5d撤消运动锻炼过程中南方鲇(Silurus meridionalis)静止代谢率(VO2rest)的变化。实验以饥饿和维持日粮条件下非运动锻炼组分别作为饥饿及摄食对照组。研究发现:饥饿和摄食对照组的VO2rest在实验过程中显著下降(P<0.05),饥饿锻炼组VO2rest在锻炼的4～15d显著上升(P<0.05),而摄食锻炼组的VO2rest相对稳定;当撤消锻炼后,饥饿和摄食锻炼组VO2rest迅速下降,与对照组无显著差异。研究表明,相对于对照组,4～7d的无氧运动锻炼导致VO2rest显著上升;而撤消锻炼后,15d的锻炼影响在3～5d内完全消除。实验还提示,与维持日粮处理比较,饥饿条件下无氧运动锻炼对VO2rest的影响更为显著。     

Energetic and life-history patterns of deep-sea benthic, benthopelagic and seamount-associated fish

A review of energy use and the life histories of deep-water demersal fishes suggests that there are two primary groups or guilds; those that live dispersed over the sea floor and those that aggregate in association with topographic features like seamounts. Dispersed deep-sea fishes typically have a body plan designed for slow cruising or 'sit and wait' predation, and are characterized by very low energy stores and metabolic rates. Scaled for body size, the metabolism of these fishes was comparable to that of bathypelagic fishes. On the other hand, aggregatory deep-water species are characterized by robust morphology and strong locomotory ability to maintain themselves in environments characterized by strong, variable currents. Their flesh has high protein and lipid but low water content. The metabolic rate of orange roughy, an aggregating deep-water species, was substantially higher than that of dispersed deep-water fishes and was comparable to that of haddock, a shelf demersal species. However, although the estimated ration of orange roughy was higher than that of dispersed demersal deep-water species, its growth rate was comparable and its growth efficiency was far lower due to its high metabolic costs. Large deep-water dispersed fish species are characterized by late maturity and an extended reproductive period, but these characteristics are less pronounced than in deep seamount-associated species, which may live in excess of 100 years.     

Effects of Calcium and Dairy on Body Composition and Weight Loss in African‐American Adults

Objective: Our objective was to determine the effects of dairy consumption on adiposity and body composition in obese African Americans. Research Methods and Procedures: We performed two randomized trials in obese African‐American adults. In the first (weight maintenance), 34 subjects were maintained on a low calcium (500 mg/d)/low dairy (<1 serving/d) or high dairy (1200 mg Ca/d diet including 3 servings of dairy) diet with no change in energy or macronutrient intake for 24 weeks. In the second trial (weight loss), 29 subjects were similarly randomized to the low or high dairy diets and placed on a caloric restriction regimen (?500 kcal/d). Results: In the first trial, body weight remained stable for both groups throughout the maintenance study. The high dairy diet resulted in decreases in total body fat (2.16 kg, p < 0.01), trunk fat (1.03 kg, p < 0.01), insulin (18.7 pM, p < 0.04), and blood pressure (6.8 mm Hg systolic, p < 0.01; 4.25 mm Hg diastolic, p < 0.01) and an increase in lean mass (1.08 kg, p < 0.04), whereas there were no significant changes in the low dairy group. In the second trial, although both diets produced significant weight and fat loss, weight and fat loss on the high dairy diet were ～2‐fold higher (p < 0.01), and loss of lean body mass was markedly reduced (p < 0.001) compared with the low dairy diet. Discussion: Substitution of calcium‐rich foods in isocaloric diets reduced adiposity and improved metabolic profiles in obese African Americans without energy restriction or weight loss and augmented weight and fat loss secondary to energy restriction.     

Effect of Ethnicity and Geographical Location on Body Weight,Dietary Restraint,and Abnormal Eating Attitudes

Previous studies have examined the effect of ethnicity on obesity, concerns about shape and weight, and attitudes about eating. We hypothesized that geographical location would also influence these variables, and that students growing up in the northern part of the United States and attending northern colleges would differ from students from the South. To examine this, we studied a random sample of 275 African-Americans (AA) and 224 white college students in the entering class of two northern colleges (University of Pittsburgh or University of Massachusetts) or two southern colleges (Augusta or Paine College). All subjects were weighed and completed the Revised Restraint Scale and the EAT-26. AA women were heavier than white women, with no differences due to geographical location. Despite being thinner, white women reported more dietary restraint than AA women. This difference between AA and white women was apparent in both northern and southern college students. In contrast, geographical location was the strongest determinant of bulimic attitudes; both men and women at northern colleges reported higher bulimia scores than those at southern schools. Thus ethnicity appears to be a major determinant of body weight and attitudes about shape and dieting, whereas geographical location appears to exert greater influence on bulimic attitudes.     

The Dependence of Crustacean Respiration Rate on Body Mass and Habitat Temperature

The respiratorion rates of Crustacea from temperate and tropical waters of the Atlantic Ocean were measured directly at habitat temperatures of 19, 25 and 29 °C. The results were analysed together with data obtained from similar investigations in previous years (Ivleva, 1977) on Crustacea from moderately cold and polar latitudes at 10, 6 and 0 °C. Variations of the values for A and k in generalized regressions (R = AWκ) for Crustacea within the temperature limits of the physiological range were shown to have quite a clear-cut and regular character. The coefficient k varied from 0.60 to 0.79 and revealed a tendency to increase as temperatures decreased. The value of A increased with rising temperature within all intervals from 0 to 30 °C. The quantitative relationship between respiration rate and temperature was evaluated by the Arrhenius equation. Statistical processing of resultant data indicated a rather close association between log A and the habitat temperature of the Crustacea but only slight deviations from the theory of empirically found values. The accelerating effect of temperature (μ) was 13 ± 0.13 keal/mol. This value was used to calculate Q₁₀, which was more convenient for practical purposes.     

短期持续限食对树麻雀体重和基础代谢率的影响及生态学意义

为探讨短期持续限食对树麻雀(Passer monanus)体重和基础代谢率的影响,及其生理适应的调节机制。以正常饲喂树麻雀为对照组(0D组,D为饥饿天数),以进食量相同和持续限食时间不同的4组(1D、3D、5D和7D)树麻雀为研究对象进行限食驯养。结果显示,体重与个体BMR间存在极显著的线性关系(r=0.512,P=0.001);5组树麻雀单位体重的基础代谢率(BMR)差异不显著,5D和7D组树麻雀的个体BMR组间差异显著(P0.05);树麻雀的体重驯养前后变化为对照组增加而4个实验组降低,驯养后,1D和7D组与对照组相比体重降低分别为显著(P0.05)和极显著(P0.01),3D和5D组相对于1D、7D组出现小幅度的上调,1～7d持续限食树麻雀的体重出现降升降的趋势。结论是:当摄食量不足时,消耗体内的能量储备和降低个体的基础能耗对缓解短期持续限食的生存压力有利,但个体适合度随之降低。体内能量储备和个体基础能耗的相应增加是树麻雀应对饥饿环境的关键,也是其重要的生存策略之一。     

A Randomized Controlled Trial of Two Different Macronutrient Profiles on Weight,Body Composition and Metabolic Parameters in Obese Adolescents Seeking Weight Loss

Objective

Adolescent obesity is difficult to treat and the optimal dietary pattern, particularly in relation to macronutrient composition, remains controversial. This study tested the effect of two structured diets with differing macronutrient composition versus control, on weight, body composition and metabolic parameters in obese adolescents.

Design

A randomized controlled trial conducted in a children’s hospital.

Methods

Eighty seven obese youth (means: age 13.6 years, BMI z-score 2.2, waist: height ratio 0.65, 69% female) completed a psychological preparedness program and were then randomized to a short term ‘structured modified carbohydrate’ (SMC, 35% carbohydrate; 30% protein; 35% fat, n = 37) or a ‘structured low fat’ (SLF, 55% carbohydrate; 20% protein; 25% fat, n = 36) or a wait listed control group (n = 14). Anthropometric, body composition and biochemical parameters were measured at randomization and after 12 weeks, and analyzed under the intention to treat principle using analysis of variance models.

Results

After 12 weeks, data was collected from 79 (91%) participants. BMI z-scores were significantly lower in both intervention groups compared to control after adjusting for baseline values, SLF vs. control, mean difference = -0.13 (95%CI = -0.18, -0.07), P<0.001; SMC vs. control, -0.14 (-0.19, -0.09), P<0.001, but there was no difference between the two intervention diet groups: SLF vs. SMC, 0.00 (-0.05, 0.04), P = 0.83.

Conclusions

Both dietary patterns resulted in similar changes in weight, body composition and metabolic improvements compared to control. The use of a structured eating system which allows flexibility but limited choices can assist in weight change and the rigid application of a low fat eating pattern is not exclusive in its efficacy.

Trial Registration

International Clinical Trials Registry ISRCTN49438757     

温度对鳊鱼静止代谢和耐低氧能力的影响

以鳊鱼(Parabramis pekinensis)幼鱼[体重(8.13±0.15)g,n=31]为研究对象,以密闭式代谢测定法分别在15、20、25、30℃条件下测定其静止代谢率(Rest Metabolic Rate,RMR),并以双线法推算临界氧浓度Pcrit等相关参数。结果显示,鳊鱼幼鱼的静止代谢水平呈随温度上升而升高的变化趋势[(132.22±4.97)mg O2/(h.kg)(15℃),(182.67±12.49)mg O2/(h.kg)(20℃),(218.44±9.20)mgO2/(h.kg)(25℃),(298.32±9.96)mg O2/(h.kg)(30℃)],除20～25℃间,其他各温度组差异显著(P0.05);Q10值均低于2(15～20℃1.91,20～25℃1.43,25～30℃1.87);本研究还发现,随着温度的升高,鳊鱼幼鱼的Pcrit逐渐下降,而临界氧饱和度Scrit则相对保守[15、20、25、30℃的Pcrit分别为(1.35±0.09)、(1.16±0.19)、(0.97±0.12)和(0.86±0.09)mg O2/L,Scrit分别为13.87%±0.74%、13.32%±1.72%、12.15%±1.35%和11.34%±0.65%。这表明,采用不同指标考察鱼类耐低氧能力可能会得到相异的结论。这种结论的不一致提示,在鱼类应对环境溶氧降低的适应中,相对溶氧水平而不是绝对溶氧水平影响并决定着鱼类的适应性进化,因此采用相对饱和度作为指标研究鱼类耐低氧能力可能更具理论价值。     

The Effect of Food Quantity on Feeding and Metabolic Expenditure in Cladocera

The effect of Chlorella concentration on total metabolic expenditure, basal metabolism and filtering and ingestion rates was studied in juvenile and adult females of three cladoceran species. No significant influence of food concentration on basal metabolism was found, whereas total metabolic expenditure depended on Chlorella concentration. Total metabolic expenditure in cladocerans was subdivided into: basal metabolism and expenditure on filtration, locomotion and specific dynamic action (SDA). Significant positive correlations were observed between expenditure on filtration and filtering rate and between expenditures on SDA and ingestion rate.     

Effect of Scalp and Facial Hair on Air Displacement Plethysmography Estimates of Percentage of Body Fat

Objective: The objective of this study was to determine the effect of body hair (scalp and facial) on air displacement plethysmography (BOD POD) estimates of percentage of body fat. Research Methods and Procedures: A total of 25 men (31.4 ± 8.0 years, 83.4 ± 12.2 kg, 181.8 ± 6.9 cm) agreed to grow a beard for 3 weeks to participate in the study. Total body density (g/cm³) and percentage of body fat were evaluated by BOD POD. To observe the effect of trapped isothermal air in body hair, BOD POD measures were performed in four conditions: criterion method (the beard was shaven and a swimcap was worn), facial hair and swimcap, facial hair and no swimcap, and no facial hair and no swimcap_. Results: The presence of only a beard (facial hair and swimcap) resulted in a significant underestimation of percentage of body fat (16.2%, 1.0618 g/cm³) vs. the criterion method (17.1%, 1.0597 g/cm³, p < 0.001). The effect of scalp hair (no swim cap worn) resulted in a significant underestimation in percentage of body fat relative to the criterion method, either with facial hair (facial hair and no swimcap; 14.8%, 1.0649 g/cm³) or without facial hair (no facial hair and no swimcap; 14.8%, 1.0650 g/cm³, p < 0.001 for both). Discussion: A significant underestimation of percentage of body fat was observed with the presence of facial hair (～1%) and scalp hair (～2.3%). This underestimation in percentage of body fat may be caused by the effect of trapped isothermal air in body hair on body‐volume estimates. Thus, excess facial hair should be kept to a minimum and a swimcap should be worn at all times to ensure accurate estimates of body fat when using the BOD POD.     

Influence of Dietary Conjugated Linoleic Acid and Fat Source on Body Fat and Apoptosis in Mice*

Objective: To determine whether altered dietary essential fatty acid (linoleic and arachidonic acid) concentrations alter sensitivity to conjugated linoleic acid (CLA)‐induced body fat loss or DNA fragmentation. Research Methods and Procedures: Mice were fed diets containing soy oil (control), coconut oil [essential fatty acid deficient (EFAD)], or fish oil (FO) for 42 days, and then diets were supplemented with a mixture of CLA isomers (0.5% of the diet) for 14 days. Body fat index, fat pad and liver weights, DNA fragmentation in adipose tissue, and fatty acid profiles of adipose tissue were determined. Results: The EFAD diet decreased (p < 0.05) linoleic and arachidonic acid in mouse adipose tissue but did not affect body fat. Dietary CLA caused a reduction (p < 0.05) in body fat. Mice fed the EFAD diet and then supplemented with CLA exhibited a greater reduction (p < 0.001) in body fat (20.21% vs. 6.94% in EFAD and EFAD + CLA‐fed mice, respectively) compared with mice fed soy oil. Dietary FO decreased linoleic acid and increased arachidonic acid in mouse adipose tissue. Mice fed FO or CLA were leaner (p < 0.05) than control mice. FO + CLA‐fed mice did not differ in body fat compared with FO‐fed mice. Adipose tissue apoptosis was increased (p < 0.001) in CLA‐supplemented mice and was not affected by fat source. Discussion: Reductions in linoleic acid concentration made mice more sensitive to CLA‐induced body fat loss only when arachidonic acid concentrations were also reduced. Dietary essential fatty acids did not affect CLA‐induced DNA fragmentation.