MAR 5

13. MAR 5: Unit Three: Dietary Change (Reading Day - No class meeting)

Assigned Work

• Kessler, The End of Overeating, Chs 1-3 (p. 3-17) (14)
• Shepard, Gordon, C21 and C27 "Flavor and Obesity" (184-192; 8)
• Recommended:

• Burkhardt Bilger, "Can Babies Learn to Love Vegetables"
• Tarragon and Moreno "Role of Endocannabinoids on Sweet Taste Perception"

In-Class

• Barbara Roll's "Volumetrics"
• Behavioral medicine, a focus of Kessler’s work. [1]
• Review of resources for SW2: Assessing Industrial Food Systems

Rolls, Barbara, "The Role of Energy Density in the Overconsumption of Fat,"

• The nutrition rock star herself. [2]

• [Framing the problem: Our evolutionary challenge, under typical conditions of more frequent food insecurity, is to seek energy (calories). In Kessler's theory, this explains the greater sensitivity of the reward system and neural response to hyperpalatable foods. Rolls is looking at the same mechanisms, but by comparing energy dense and nutrient dense foods.]

• Energy density theory - High energy dense, low volume foods cause lower levels of satiety than nutrient dense foods of similar palatability. Or, diff macronutrients have different consumption patterns and satiety effects.

• Energy density is calories/volume of food.

• Pre-load studies - test subjects are given food before a meal time (the pre-load) and then mealtime consumption is observed. Pre-loads that reduce voluntary consumption are inferred to have greater satiety.

• Back to "Does fat make you fat?" - Maybe the energy density of fat, like the density of highly palatable foods, makes you less satiated, but it's not the fat itself that is less satisfying, rather the energy density (aka ratio of volume/cal). Old idea: fat has a unique ability to make you fat. But these studies did not control for the confounding effect that energy dense foods have less weight and volume that nutrient dense foods. So we drew the wrong conclusion: fat makes you fat. Rather, all energy dense foods have higher ratios of calories to volume. You are sated by volume.

• New research, when controlled for energy density, fats and carbs have similar effects on satiety (measured as subsequent food intake after a "pre load" of some food under study). So, "fast carbs" and fats have similar effects. It's not fat that makes you fat, it's palatable, energy dense foods -- because they are less stating, we eating more of them. Another way to put it is that we eat for volume.

• water as beverage vs. water in foods (as in youtube) - Casserole v. soup study water study. Added volume from water in soup reduced subsequent intake, but not if water was present as a beverage.

• 269S: studies suggesting that we eat by weight, not by energy intake. So the same amount of food by weight, if energy dense, will increase our calorie intake.

• Note: High volume, high nutrition, low density foods are typical of humble cuisines. Grains, legumes, water filled vegetables.

Shepard, C21

C21: Flavor and Obesity

• considers the case of french fries in relation to the flavor perception system. Salt, fat, and sweetness (SFS). Discusses the meat flavor from tallow, now artificially added. Adds in the rest of the typical fast food meal. Chased with coffee and a cookie. Coffee has over 600 volatile molecules. Point: the fast food meal involves sensory overload.

• Overeating:

• sensory overload;
• caloric density; reduced roughage.
• But also “Sensory-specific satiety” . Single flavors diminish appetite while multiple flavors amplify it. You can eat more food if it includes multiple flavors. The complexity of industrial flavors increases our ability to overconsume them. 187
• long-term overstimulation of skin and membranes of the lips and mouth. Interesting research shows obese test subjects have more activation of these areas even while not eating. [this supports the idea of a learned behavior from food conditioning]
• Conditioned overeating: Other research by Dana Small. You can induce extra eating in rats with conditioned stimuli (bell). Humans have wide field of potential conditioning stimuli.
• Other research suggests that ineffective inhibitory circuits play a role in obesity.
• Others speculate that the reward value of food for obese is too low. The brain doesn’t register enough pleasure from a normal diet.
• Kessler: combination of SFS culprit (note that in Kessler’s theory several of the above theories are included.)

Kessler, The End of Overeating, Chs 1-7 (3-45; 42)

[Kessler's basic argument:

• Explaining overweight and obesity:

• Highly palatable foods (high in SFS, little chewing, slurpable...) can overwhelm our homeostatic system, which would otherwise maintain consumption levels that sustain normal weight.
• This leads to overconsumption.
• The Food industry understands this and uses food science to created and market highly palatable foods.
• C: This provides a good explanation for overweight and obesity in the US.]

• Some comments about approaching "unhealthy eating patterns" (expand list), some baseline data, and Kessler's basic theory.

C1

• obesity trend of the 1980s. by late 80s 1/3 of pop bt. 20 and 74 overweight. (2017: 42.4% obese (note: not just overweight). J

• Historic comparisons: 1960-2000, average weight of women in their 20s goes from 128 to 157. Also other deciles. Data also revealed that some people were gaining a lot more than the average. In other words, the distribution was changing. Overweight people became disproportionately overweight. More outliers.

C2

• obesity is the result of eating too much food. Confusing to separate metabolism, etc. People underreport consumption. Studies to support claims. P.8 [Note some criticisms here: microbiome effects. Others argue that metabolic changes do occur to make significant weight reduction difficult.]

• Homeostasis: tendency of body systems to maintain bodily states within a particular range of variation. Communication occurs throughout the body to this end. But homeostasis can’t explain weight gain. Homeostasic system can be overwhelmed by the “reward system”. Anticipations of reward motivate exertion.

• Some animal studies show direct stimulation of reward seeking behavior. Stimulate the far-lateral hypothalamus” and animals overeat. Even to cross electrified floor. [Note basic explanation here.]

• Can some kinds of food stimulate us to keep eating?

C3

• Palatability - def. a food with an agreeable taste, but in food science - a food that motivates more consumption.

• Palatable foods engage sugar, salt, and fat, but also sensory cues. Research (13) on combined effects of sugar and fat (Drewnowski). Underlies many palatable features of food. Combinations of fat and sugar chosen over other mixes. Can make food hyperpalatable. Example of "hyper-palatability" in industry and as a research concept in food science.

• 15: Research (rat study) showing that consumption of SFS optimized foods increases further consumption. Both obesity prone and obesity resistant rats over ate high SF foods.

• Sclafani research. Neat fruit-loop lab detail. Just chillin' with his rats.: feeding rats a supermarket sample of palatable food makes them obese.

• Some palatability research not in the reading:

• Can the Palatability of Healthy, Satiety-Promoting Foods Increase with Repeated Exposure during Weight Loss?

C4

• Food industry experts corroborate Kessler’s point about SFS foods and overeating. It’s their strategy.

• ”Layering” SFS: examples of foods that layer S F and S. (Gordy's lemon chicken, much like p. 20 "Chicken Pot Stickers"). List: White Chocolate Mocha Frapp, Bloomin’ Onions, Salads with high SFS dressings (“fat with a little lettuce”). [Remember, restaurants don’t have to provide nutritional information.]

C5

• Critical of “set point theory” more interested in version he calls “settling point” theory. A kind of equilibrium between appetite (which both a drive to eat and capacity to be satisfied and expenditure - physical work and body that burns calories effectively. Constant access to highly palatable foods drives up settling point. (Kind of acknowledges that there is wide variation in the hold (capture) of high SFS foods.

• p. 25: Discussion with other people who find weight control challenging. note descriptions. Sight of favorite SFS foods causes salivation and tingling sensations. Important qualification: Food cravings are not unique to overweight people.

C6

• More theory: Reinforcing foods

• Rewarding foods are reinforcing. Reinforcing measured by willingness to work for substance and whether other stimuli can become associated with it. (Shepard’s account helps show how this works.)

• SFS Foods can be an effective reward even in the absence of hunger. Animal studies to show this. Research: rats will press levers to get SFS foods. A lot. P. 30. Confirms the idea that combinations of fat and sugar increase willingness to work for reward. Approaches reward structure of cocaine.

• “Conditioned place paradigm”. — tendency to prefer the location in which a reward was experienced. Party food at sport viewing events, for example. Rat study involving more and less preferred spaces. High SFS foods can override location preference.

• Other influences: portion, concentration of rewarding ingredients, variety.

C7

• Neural account of high SFS / palatable foods. Neuron encodes when it fires more often from a stimuli. Complex patterns can be encoded from food experience.

• Taste is predominant. “Orosensory self-stimulation”. Opioid circuitry stimulated by food. P. 37: mechanisms of the reward system. Imp of nucleus accumbens - a neural structure that governs reward.

• Claims there is a mutually reinforcing effect between highly palatable foods and opioid circuits. Explains how emotional eating can reduce the pain associated with stress and depression.

• Some evidence (Wooley p. 38) that highly palatable foods interfere with or override taste specific satiety tendency to get sated by a single taste. SFS combinations can override taste specific satiety. Stimulation of the opioid circuits in animals overrode boredom with single taste.