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Medium-chain triglycerides (MCT) have unique characteristics relating to energy density and metabolism giving them advantages over more common long-chain triglycerides (LCT). Human consumption of MCT oils is low since naturally occurring sources of MCTs are rare; however, those sources include milk fat, palm kernel oil and coconut oil.

MCTs are less energy dense and highly ketogenic compared to LCTs. First, the energy density of MCTs is less than that of LCTs due to their shorter chain length. MCTs provide about ten percent fewer calories than LCTs; 8.3 Cal per gram for MCTs versus 9 Cal per gram for LCTs. MCTs also differ from LCTs in their metabolic pathway because they are easily oxidized and utilized as energy, with little tendency to deposit as body fat. Consequently, the intake of MCTs can decrease caloric intake and potentially decrease body weight and body fat in the long term.
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The literature supports that MCT oil increases energy expenditure and decreases body fat in the majority of studies in both animals and humans. In addition, MCTs may have a greater effect in overweight subjects as opposed to normal weight or obese subjects. Overall, short-term intakes of MCT oil have been shown to promote weight loss; however, chronic intakes of MCTs have shown various effects on energy expenditure, body weight, and fat mass. Yet, appetite control may play a bigger role in weight loss in long-term feedings of MCTs. The exact mechanism for the satiating effects of MCT is unknown, but may perhaps be explained by the distinctive energy density of MCT or the increase in fat oxidation. These studies suggest that replacing LCT with MCT oil could generate body fat loss over long periods of time, with or without reduced energy intake.

Studies provide varying results concerning the influence of MCT on lipid metabolism such as increased TG concentrations. In addition, several studies have reported that MCTs do not affect blood cholesterol levels; however, others have reported hypercholesterolemic effects of MCTs due to their high saturated fat content. Therefore, the incorporation of other functional foods, such as conventional oils, essential fatty acids or plant sterol may minimize the risk of negative effects of MCT on blood lipids while optimizing decreases in body weight and body fat accumulation. In addition, the ingestion of MCT incorporated into the diet does not appear to cause any adverse symptoms.

MCTs are easily included in food products without negatively affecting their taste or producing undesirable effects. MCT production is cost-effective compared to other oil-based functional foods. The short-term efficacy of MCT is proven; however, long-term effects of MCT still need to be examined more carefully. Overall, MCT shows a good AECES model and demonstrates the greatest potential for use as a functional fat for weight control.

All cooking oils naturally contain small quantities of diacylglycerols (DAG), ranging from 0.8% in rapeseed oil to 9.5% in cottonseed oil.39 In addition, DAG is produced in the digestive tract as a metabolic intermediate, as 1,2-diacyl-sn-glycerol (1,2-DAG) or 2,3-diacyl-sn-glycerol (2,3-DAG), after the ingestion of TG.40 In recent years manufacturers have developed an enzymatic process to produce 1,3-diacyl-sn-glycerol (1,3-DAG) by migration of the acyl group with the reverse reaction of the 1,3-specific lipase. DAG oil can be easily incorporated into food products since it is similar in taste, appearance, and fatty acid composition to other oils.

It is the specific structural differences of DAG isomers and not the fatty acid composition of DAG or TG that appear to explain the different action on lipid metabolism and body weight. The main end products of lipase action on 1,3-DAG are glycerol and free fatty acids, which may be less readily re-synthesized to chylomicron TG. Moreover, larger amounts of fatty acids from digested DAG may be released into the portal circulation rather than being incorporated into chylomicrons, compared with TG oils. In addition to producing lower TG content of chylomicrons, lower serum TG levels in a fasted state and in the postprandial state occur after DAG ingestion. This hepatic exposure to fatty acids by increasing DAG intake may lead to greater fat oxidation by the liver than following TG intake. Enhanced fat oxidation may lead to increased satiety. Thus, decreasing caloric intake may induce a decrease in weight and fat loss in long-term DAG feedings.

While certain studies indicate that 1,3-DAG has a positive outcome in animal and human trials, other studies show no effect on body weight63-67 or TG levels. This lack of effect may be due to insufficient doses used (10% in the diet) or the heterogeneity across subjects used including overweight or obese versus normal weight individuals. Overweight and obese subjects could have defective fat oxidation; thus, higher fat oxidation may produce greater weight loss. Although the use of DAG oils for weight control is promising, much remains to be clarified regarding the mechanism of dietary DAG.

DAG oil studies do not indicate any severe adverse health effects related to its consumption. However, it still remains to be seen how DAG oil intake will affect humans on a long-term basis as well as synergistically with other nutrients.

Overall, DAG oils are easily incorporated into foods without affecting palatability, but have slightly higher costs than conventional oils. The AECES model for DAG shows it being a generally appropriate functional food for weight control; however, DAG oil has not yet been a huge success with consumer acceptance due to conflicting studies on the efficacy of the product. Overall, DAG oil demonstrates potential as a weight loss agent, but future research is needed to elucidate mechanisms responsible for its action on weight loss.

Conjugated linoleic acid (CLA) is a collective term for a group of positional and geometrical conjugated dienoic isomers of linoleic acid that are found in dairy products and meat. The cis-9, trans-11 CLA is the principal dietary CLA form, but lower levels of the other isomers (trans-10, cis-12 CLA, trans-9, trans-11 CLA, and trans-10, trans-12-CLA) are present in food CLA sources. Naturally, CLA is produced in the rumen of ruminant animals by the fermentative bacteria that isomerize linoleic acid into CLA.

Mechanisms of action of CLA include: enhanced thermogenesis, increased satiety, augmented fat oxidation, reduced fat cell size as well as fat deposition, increased apoptosis of adipocytes and altered preadipocyte differentiation. Potentially, the combination or additive effects of all these mechanisms of action of CLA may lead to changes in weight and body fat, as no single mechanism fully explains CLA action.

Studies have shown that CLA, specifically the trans-10, cis-12 isomer, can reduce body weight and fat mass. Most animal studies associated with feeding CLA have shown that CLA lowers body fat and energy retention as well as increases energy expenditure, thereby decreasing weight; yet, others have shown no effects on weight. This may be due to the dose or the CLA isomers used in animal studies. Results demonstrate that body weight and/or fat mass of animals were not affected when they were supplemented with low amounts of CLA mixture (0.5% in the diet), which contained about equal amounts of the trans-10, cis-12 isomer and cis-9, trans-11 isomer. Yet, weight gain was similar to control when high amounts of CLA mixture with mostly the cis-9, trans-11 isomer were given. However, most human studies have not been able to replicate the magnitude of weight lost. Only a few human studies suggest that CLA supplementation has reduced body fat and other studies did not show any effect. The variety of species used in studies may also explain the discrepancy of results obtained.

In animals, CLA supplements appear to have some undesirable side effects such as induced insulin resistance as well as fatty liver and spleen. These animal studies also demonstrate that CLA may have detrimental effects on plasma lipids. Human studies also show evidence that CLA may adversely influence health, in particular insulin sensitivity and blood lipids, but the results are conflicting. CLA is widely available in capsule form that improves its oxidative stability, therefore having an appropriate matrix, cost, and sensory quality for consumers. However, the efficacy of CLA is questionable because the animal evidence is more convincing than the human data. The lack of clarity on the mechanism of action can explain the inconsistencies in the research results. In addition, human studies should be carried out to determine the long-term effects of CLA and whether any adverse outcomes occur. In summary, the data available from literature demonstrates a poor AECES model. More research is needed to investigate the efficacy and the safety aspects before CLA will have optimal consumer acceptance.

Numerous functional foods have been examined for their potential as weight-loss agents. To evaluate the future of functional foods, the AECES model has been developed to verify the following: Acceptability, Ease of formatting, Cost-effectiveness, Efficacy and Safety. The goal of this review is to assess three oil-based weightloss functional foods, including: conjugated linoleic acid (CLA), diacylglycerols (DAG) and medium-chain triglycerides (MCT), in terms of the AECES model for consumer acceptability. First, CLA is an overall poor AECES model due to its weaknesses in the efficacy and safety aspects since most of the evidence of CLA is based on animal studies. Secondly, oils rich in DAG, specifically the 1,3-isoform, have an appropriate AECES model. Although, the efficacy still needs more research to determine the exact mechanisms of action for DAG-rich oils. Thirdly, MCT oils exhibit a good AECES model; nevertheless, the long-term efficacy of MCT needs to be further explored. The capability of these three functional oils as effective anti-obesity agents is substantial, yet further investigation should be conducted to determine the missing gaps in research and to accomplish satisfactory AECES model for market acceptance.

Obesity is at the forefront of global health issues as it directly contributes to many chronic illnesses. Excess weight is the result of an imbalance between energy intake (EI) and energy expenditure (EE), by which surplus EI is stored as triacylglycerol (TG) in adipose tissue. Overweight and obese consumers often turn to natural health products to help support and maintain their weightloss program. Although the weight management industry is large, most of the weight-loss supplements on the market have not been scientifically proven to be effective.(1) Recently, several natural health products have shown promise in the treatment of obesity, some of which are oil rich in conjugated linoleic acid (CLA), diacylglycerols (DAG) and mediumchain triglycerides (MCT).

The AECES model has been developed by experts in the nutrition field to determine the future of functional foods in the marketplace. Five criteria can be used to evaluate the potential of functional foods and nutraceuticals, including: acceptability, ease of formatting, cost-effectiveness, efficacy and safety.(2) This is known as the AECES model (Figure 1). A “good” AECES model includes the following characteristics (Table 1): easily incorporated into a suitable matrix and diet, acceptable cost to manufacturer and consumer, ability to produce a desired effect and lack of major side effects. All the components of the AECES model are closely interrelated sharing the same final goal: consumer acceptability of the functional food. The range of “appropriate” to “poor” in the AECES model would be assigned to functional foods that either lack data or provide some negative research results in one or more of the model criteria, which would lead to decreased consumer acceptance of the functional food. The purpose of this review is to examine the role of functional foods in health promotion, in relation to body weight and circulating lipid levels, such as oils rich in CLA, DAG and MCT oils. Particularly, this review is intended to evaluate these functional oils in terms of the AECES model for consumer suitability.

Impact of the Take Charge Course
Gains in health status were achieved both during the 8 week course and into the second year following class completion (Table 2). The average weight lost during the 8 week course was 4 pounds (n=16; p<0.05; range= +5 to –18 pounds). Longer-term weight loss is available for follow-up periods ranging from 3 months post graduation to 2 years later (mean follow-up period =11 months). Using the last known weight as compared to baseline, there was an average 14 pound weight loss (n=16; p<0.01; range= +13 to –52). The ratio of weight reducers to weight gainers during the class period was 2.25:1 and in the follow-up period was 4.3:1. Group support and food-related content were rated most important by participants in the class. English and Spanish speaking participants ranked support, cooking information, and health information similarly high in importance. Although exercise and relaxation were seen as much less important components of the course, according to long-term follow-up interviews, exercise practices increased following the course. One third of the respondents wanted instruction on exercises appropriate to their disabilities (joint problems, hip pain, pacemaker, use of a cane). Most participants continued using class recipes and techniques for reducing fat.

Drop-outs (attended 2-5 sessions) were surveyed to see whether objections to the class caused their limited attendance. Explanations for low attendance were personal and unrelated to the course. In spite of lower attendance, these participants were able to list concepts they learned from the course and behaviors they changed as a result of their participation.

Take Charge instructors realized early in the course that eating habits of patients did not result from a lack of information but instead reflected larger psychosocial issues. The course was not designed to cure eating disorders, but by combining motivational activities with health education was able to successfully circumvent emotional factors that led to the unhealthy diet choices of many of the patients.

The evaluation interviewers summarized participant response to the intervention as “effusively happy.” This satisfaction is credited in large part to empowerment derived from the social support and self-esteem enhancing activities. The instructors credit the wholistic approach of the Take Charge course for impacting the lives of participants beyond its primary aim of encouraging patients to adopt healthy diets. For many participants, the class provided the impetus to pursue new careers and fulfill old aspirations, from enrolling in piano classes to starting a home business. Some Alumni members returned to teach subsequent classes, taking over teaching responsibilities from the instructors. The alumni instructors were recruited for their natural leadership and commitment to the class; all had completed high school, some had additional training or education. These alumni instructors served as role models for participants, enhanced the cultural content of the class, and validated the impact of the course, making their involvement invaluable.

Patient Profile
Participants in the English language class were primarily African American and ranged from young adults to great grandmothers. A majority of the participants were middle-aged or older and lived alone, while some were raising their grandchildren. Many participants were on disability as a result of their weight related comorbidities and spent much of their time alone at home.
Participants in the Spanish language class were more likely to be living in families. Most of them were women with husbands and younger children. A majority were recent immigrants from Mexico or Central America. Although this group was also overweight and had related diseases such as hypertension and diabetes, they were less likely to be as obese as participants in the English language group.

The Class Curriculum
The curriculum of the Take Charge class was created to reflect the wholistic approach taken by Family Medicine towards patient needs and it emphasized the role of biopsychosocial factors in health. The course curriculum consisted of diet education, fitness exercise, and empowerment and motivational activities. Medical issues related to obesity, such as the relationship between fat and heart disease, were taught by the physician instructor during class discussions. The physician instructor also addressed individual health questions of patients and referred them to their primary care physicians for follow-up as needed.

Participants were instructed to follow a very low-fat, high fiber vegetarian diet, restricting daily fat intake to about 20 grams. The content of the diet education included cooking demonstrations and samples, healthy food displays, and information on shopping, reading labels, and calculating fat and fiber gram intake.

The class devoted time to low impact aerobic exercise, stretching, deep breathing, and meditation relaxation. Empowerment activities designed to enhance self-esteem, raise consciousness, motivate behavior change, and provide support were also regular curriculum features. Active peer support was delivered through group “go-rounds” and a “listening exercise.” The focus of the go-rounds was to provide each person time to share with the group and learn about others. The one-on-one listening exercise allowed participants to explore thoughts and feelings with a partner who practiced listening without offering advice. To expand this peer support beyond the classroom, participants were encouraged early in the program to exchange contact information and set up walking dates. As the class progressed, exercises like identifying “10 things I want to do in this lifetime” were incorporated into the Take Charge curriculum to address the deeper motivational needs of participants, especially those on disability who had been out of work for several years. The instructors felt that participants found lifestyle change easier when they were occupied with other lifetime goals and were busy with activities that satisfied them and kept their minds off food.

The lack of onsite educational options, and absence of referral resources, prompted faculty from the USC/California Hospital Family Medicine Residency Program to develop the Take Charge class. The course was designed to promote lifestyle change through a group intervention in an overweight, inner-city minority patient population experiencing a variety of lifestyle-influenced chronic diseases. This paper uses a case study to illustrate the health education program.

Methods
The case study was developed by the course instructors with the assistance of an external researcher using quantitative and qualitative assessments. Information was triangulated to increase the validity of findings.

The course was delivered to 13 cohorts of patients. Weights were collected from cohorts 1 and 2 (n= 31) to measure change before and after the eight week course, as well as at three month follow-up intervals, using one-tailed paired t-tests for significance. Evaluation questionnaires measuring individual perceptions of class content were given to cohorts 4, 5, and 6 on the last day of the course (n= 34: 25 Spanish, 9 English). Long-term follow-up phone interviews were also conducted. External interviewers were used to promote honest responses. The follow-up interviews were designed to control for the temporal dimensions of course acceptance and life-style change. Phone interviews were conducted with cohorts 1, 2, 3 and 5 (n= 49). Average time since graduation was 21 months (range = 12-26). Since the course instructors thought there might be an upward bias in graduation-day evaluation responses, the long-term evaluation sample included both graduates and “drop-outs” and analyses compared the responses of each group.

The Lifestyle Change Intervention
The Take Charge course was developed and facilitated by a Family Physician and a doctor of Public Health. The course consisted of 2-hour sessions held on a weekly basis for eight weeks. Courses were conducted separately in English and Spanish.

California Hospital is home to a Family Medicine residency which operates a primary care Family Practice Center (FPC) across the street from the hospital near the garment district of Los Angeles. For the Take Charge class, faculty members outfitted a large conference room at the FPC, normally used for physician education, with large chairs, some cooking equipment, and educational materials.

FPC patients were referred to the class by their primary care providers. As word of the class spread, patients from neighboring community clinics were also referred. To make the classes more accessible for these outside patients, some sessions were conducted offsite. 124 participants were enrolled in 13 cohorts over four years. The average weight of participants was 237 pounds (95% confidence interval=217-258, range=122-503). This population had multiple related co-morbidities, including: hypertension, coronary artery disease, congestive heart failure, hyperlipidemia, diabetes, arthritis, chronic back pain, depression, and hypothyroidism. Other co-morbidities included: anemia, addiction, blindness, chronic obstructive pulmonary disease, glaucoma, lupus, multiple sclerosis, and seizure disorder.

Participants attending six or more of the eight sessions received graduation certificates. Seventy-four participants graduated and were invited to join alumni activities.

In low-income minority communities, there is high prevalence and clustering of obesity, coronary heart disease, dyslipidemia, hypertension and diabetes mellitus. Evidence suggests one way to treat and prevent these conditions is through a very low-fat, high fiber, vegetarian diet. A feasibility study was conducted to determine whether inner-city African American and Latino patients will accept a low-fat vegetarian diet and to assess attitudes about the life-style intervention. Reductions in fat and animal products were acceptable, though complete conversion to vegetarianism was not. Meanwhile, group support was the most highly rated component of the class. Contrary to common perceptions of immigrants needing to maintain traditional habits, the Latino participants enthusiastically adopted new concepts and incorporated new recipes into their diet. Weight loss was achieved during the 8 week course and continued through 18 month follow-up. It appears that individual empowerment through the group intervention, coupled with simple diet messages, supported life-style change in a high-risk group.
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Several studies suggest that the optimal diet for prevention as well as treatment of obesity, dyslipidemia, coronary artery disease, hypertension and diabetes is a very low-fat, high-fiber, vegetarian or near-vegetarian diet (Anderson, Gustafson, Bryant, & Tietyeb-Clark, 1987; Barnard, 1991; Barnard, Jung, & Inkeles, 1994; McDougall, Litzau, Haver, Saunders, & Spillers, 1995; Ornish et al., 1998; Singh, Rastogi, Verma, & et al, 1992). However, most physicians stop short of prescribing such diets for their patients because they believe that patients will not accept a vegetarian diet or one that is very low in fat. Contrary to this view held by many physicians, several studies indicate that patients can and will accept such diets, both in the short term (Barnard et al., 1994; McDougall et al., 1995) and in the long-term (Anderson et al., 1987; Ornish et al., 1998) subsequently experiencing several positive results, such as improved cholesterol, diabetes control, weight loss, and regression of coronary artery disease. A program for Native Hawaiians promoting low fat traditional foods without calorie restriction demonstrated similar long-term success (Shintani, Beckham, Tang, O’Connor, & Hughes, 1999). There is nothing in the literature regarding acceptance of such diets in low-income Latino and African American communities in the United States. This paper describes a health intervention program designed for low-income minority patients and its impact on members of these communities.

Los Angeles is home to a diverse population. In the inner-city, residents are predominantly low-income Latino or African American. Income, race and ethnicity are associated with a higher prevalence of common lifestyle related chronic diseases, and a greater burden of complications and mortality from them.(U.S. Department of Health and Human Services, 2003). The prevalence of diabetes, coronary heart disease, and hypertension, for example, are higher in Hispanics and Blacks than in Non-Hispanic whites (Centers for Disease Control, 2003). These problems are believed to be more aggravated by limited resources in the inner-city for lifestyle change: food choices in restaurants and supermarkets are more limited, opportunities for exercise and healthy recreation are scarce, and education classes are difficult to access. Lifestyle and disease management classes offered by some health plans and community agencies remain underutilized by inner-city patients in Los Angeles because patients are often faced with difficulties in accessing classes offered across town or feel compelled to restrict their movement due to safety concerns in certain neighborhoods.