Setting Fat Goals for the Diet
Nutrition research suggests that Americans should minimize their consumption of trans fatty acids and avoid using polyunsaturated fatty acids for frying and high-temperature cooking so they minimize the formation of potentially toxic lipid peroxides [8, p. 6]. Saturated fats may not be as harmful as commonly believed but high-fat processed foods do not belong in a bariatric surgery patient’s diet pre- and postsurgery.
High-fat processed foods have contributed to the accelerated increase in obesity throughout the United States during the past 25 years. New evidence is showing that saturated fat from animal foods—butter, cheese, red meat—may not be the cause of obesity. Hydrogenated vegetable oils are detrimental to human health because they contain trans fats, which cause inflammation . They entered the food supply almost a century ago when a chemist reacted liquid vegetable oil with hydrogen to make “substitute butter” called margarine. This processing then produced products like Crisco® (to replace lard) and sticks of margarine (to replace butter). In the 1950s, hydrogenated oils were cheap and shelf stable so cakes, pies, cookies, and crackers could have a shelf life of 3-12 months.
Trans fat can be found in vegetable shortenings, margarines, crackers, cookies, and snack foods, which are fried in partially hydrogenated oils. A small amount of trans fat is formed naturally in some animal-based foods . Trans fats raise the risk of coronary heart disease. Major food sources of trans fats in the American diet  are
- • 40% cakes, cookies, crackers, pies, bread
- • 17% margarine
- • 8% fried potatoes
- • 5% potato chips, corn chips, popcorn
- • 4% household shortening
- • 3% salad dressings
- • 1% breakfast cereals
The saturated fat and cholesterol myth started in 1913 with a study by Nikolai Anitschkov, MD, on rabbits fed with eggs that caused atherosclerosis. Rabbits are vegetarian and do not have a biochemical mechanism for handling cholesterol in animal foods but it took until 1965 for this research to get discounted  and another 40 years for the misconception that animal fats are heart neutral and have no effect on cholesterol/high-density lipoprotein (HDL) ratio or heart disease to become public knowledge . They do provide calories so low-fat animal products need to be chosen for weight reduction.
Animal fats are a mixture of saturated and unsaturated fats according to Professor Fred A. Kummerow. Beef fat is 54% unsaturated, lard is 60% unsaturated, and chicken fat is 70% unsaturated . Therefore, chicken would be easier for bariatric patients to digest postsurgery but lean red meat is not and needs to be avoided. Frank Hu, senior author of a recent study on weight loss, indicated that weight loss diets should be tailored to food preferences with less emphasis on low-fat food choices . Deirde Tobias, ScD, also agrees in a systematic review and meta-analysis of randomized controlled trials that compare various weight loss interventions .
Fat contains more than twice the calories per gram of carbohydrates and protein but higher fat diets provide higher satiety and may improve long-term adherence to healthier diet choices. Olive oil and avocados can contribute to a balance of omega 3-6-9 fatty acids in the diet.