Why We Eat What We Do – Economic Influences on Eating

Fundamental Nature of Eating

  • Eating = a biologically essential, daily human behavior
    • Survival requirement: intake of energy & nutrients
    • Most people eat several times per day → repeated decision-making events
  • Multifaceted motivations (Page 2)
    • Health & disease prevention
    • Physiological signals (hunger, satiety, hormonal cues)
    • Pleasure & reward pathways (taste, hedonic value)
    • Emotional comfort & mood regulation
    • Socialization (family, peers, cultural rituals)
    • Religious / cultural prescriptions and proscriptions

Health-Centered Eating Patterns

  • Adherence to Dietary Guidelines for Americans (DGAs) → lower risk of chronic disease (e.g., coronary heart disease)
    • Citation: Mozaffarian, 20162016, Circulation 133:187–225133:187–225 (Page 3)
  • Mechanistic pathways linking foods → physiological outcomes (Page 4)
    • Nutrient/food categories:
      • Sugary beverages & refined starches → ↑\uparrow liver fat synthesis, insulin resistance, systemic inflammation
      • Fruits/vegetables/nuts → ↓\downarrow oxidative stress; provide minerals, antioxidants, phytochemicals
      • Fish & shellfish → improve endothelial function, blood lipids
      • Coffee/tea/alcohol (moderate) → potential cardiometabolic benefits
    • Outcomes monitored: blood pressure, lipid profile, thrombosis, brain reward, gut microbiome, adipocyte function, etc.
  • Hippocratic maxim: “Let food be thy medicine and medicine be thy food” (≈ 450 BC450\,\text{BC}) underscores ancient recognition of diet–health nexus.

Beyond Health: Day-to-Day Determinants (Page 5)

  • Immediate drivers when selecting foods:
    • Sensory qualities (taste, aroma, texture)
    • Emotional state (stress, happiness, fatigue)
    • Convenience & time required
    • Social influences (family meals, peer norms)
    • Monetary price & household budget
  • Meal timing cues: habitual clock time ("it’s lunch time"), physiological hunger, seasonal food availability, and local access environments

Economic Perspective: Cost as a Central Constraint

Classic Quote (Page 6)

“As long as a meal of grilled chicken, broccoli, and fresh fruit costs more and is less convenient than the less healthy options, the battle for obesity will be lost.” – The Lancet 20042004
• Example price contrast: fast-food meal ≈$5.75\approx\$5.75 vs. healthy meal ≈$7.50\approx\$7.50 (inflation-adjusted 20242024 figures)

Key Research Questions (Page 7)

  • Do healthy diets cost more?
  • How do perceived vs. actual costs differ?
  • Role of USDA Thrifty Food Plan (TFP) in defining an “affordable” nutritious basket
  • Interaction of cost with convenience & time, especially in low-income households

Four Primary Purchase Motivations (Page 8)

  1. Taste
  2. Price (weighted higher in low-income groups)
  3. Nutrition knowledge/concern
  4. Convenience (time, effort, storage, cleanup)

Conceptual Map (Page 9 – Drewnowski & Darmon 20052005)

  • Determinants → food purchases → physiology/metabolism → health outcomes
    • Today’s lecture focus: Cost\text{Cost}
    • Next lecture: Convenience\text{Convenience}

Household Food Budgets (Page 10)

  • Average U.S. family of four grocery need: $900–$1000\$900–\$1000 per month (USDA 20232023)
  • Other unavoidable monthly items: housing, utilities, child care, transport, healthcare, education, debt service → tight residual funds for food among low-income families

Classroom Exercise Prices (Page 11)

  • Listed examples (a–j) ranging $3.28–$8.47\$3.28 – \$8.47 illustrate variability of single-item costs; reinforces need for price awareness when budgeting.

Poverty Simulation (Page 12)

  • Hypothetical constraint: only $20\$20 to feed oneself for an entire week
    • Requires strategic selection of inexpensive, calorie-dense, shelf-stable foods (eg. dried beans, rice, oats)
    • Implications: potential micronutrient gaps, monotony, social exclusion, psychological stress

Income Elasticity of Food Spending (Page 14)

  • Engel’s law manifestation:
    • As household income rises → absolute spendingonfoodspending on food\uparrow
    • But proportion of income spent on food \downarrow (declining share)
  • U.S. average: 11\%ofincomeonfood;householdsinpoverty:of income on food; households in poverty:>30\% (USDA-ERS)

Global Context (Page 15)

  • Map: % of per-capita GDP spent on at-home food 2018
    • High-income nations: \le 5\%
    • Low-income nations: >25\%
    → Economic development reduces relative food cost burden.

Energy Density vs. Monetary Cost

Core Observations (Pages 16–18)

  • Lower-nutrient, energy-dense foods (fats/oils, added sugars) are cheaper per kcal than nutrient-dense options (fruit, vegetables).
  • Graph (Page 17 – Drewnowski 2018)showspositiveslope:) shows positive slope:\text{Energy density}(kcal/(kcal/100\,g)↑as) ↑ as\text{cost per 100 kcal} ↓.
    • Bubbles: food groups (vegetables lowest ED & high cost/100 kcal; fats highest ED & lowest cost).
  • Price metric paradox:
    • \text{Price per kcal} makes fruit/veg look expensive because they supply few calories.
    • \text{Price per edible weight or portion} makes grains, fruit/veg, dairy appear inexpensive relative to meats/processed foods.

Illustrative Price Points

  • Head of lettuce =\$1.89deliveringdelivering90\,\text{kcal} → \$0.02/\text{kcal}
  • Packaged snack =\$5.39deliveringdelivering390\,\text{kcal} → \$0.01/\text{kcal}
  • Broccoli \approx\$0.51/\text{lb}vs.processeddelimeatvs. processed deli meat\approx\$11.00/\text{lb} (weight basis).

Perception, Culture, and Social Signals (Pages 19–20)

  • Low-income consumers cite high perceived cost of nutritious items (produce, lean meats) as main barrier.
    • Strategy used: purchase cheaper/fattier meat cuts rather than reduce meat quantity.
  • Perceived price importance correlates with more energy-dense diet even after controlling for nutrition attitude (Drewnowski & Darmon 2015).
  • Cultural acceptability often outranks nutrition: desire to mimic mainstream societal eating patterns; brand prestige can override generic savings (Dowler & O’Connor 2012).

Affordable Nutrient-Dense Choices (Page 21–22)

  • Items meeting DGAs yet budget-friendly:
    • Tomato juice/soup; root veg (potatoes \$0.16perper½\,cup, carrots);
    • Canned/frozen produce; dried beans/lentils \$0.18perper¼\,cup dry;
    • Whole-grain cereals; brown rice \$0.07perper¼\,cup dry;
    • Eggs \$0.15 per large; canned fish; milk; organ meats.

USDA Thrifty Food Plan (TFP) – Cost Benchmarks (Pages 23–26)

  • February 2025 average weekly & monthly costs (selected rows):
    • Child 1yr:yr:\$25.70/wk(/wk (\$111.60 /mo )
    • Female 20–50yr:yr:\$57.10 /wk
    • Male 20–50yr:yr:\$71.60 /wk
    • Reference family (2 adults 20–50+2kids+ 2 kids6–11):):\$229.70/wk,/wk,\$995.50 /mo
  • TFP provides detailed 7-day menu (Pages 24–25) featuring inexpensive staple patterns (orange juice, RTE cereal, bagels, turkey chili, rice pudding, beef pot roast, etc.)
  • Critiques (Page 26):
    • Formulaic inflation adjustments ignore modern price shifts & dietary trends.
    • Underestimates cost of many items; assumes minimal processed/away-from-home foods.
    • Menu monotony & palatability concerns.

Mathematical Requirements (Page 27)

To meet TFP on budget, household must:
\text{food\ waste}=0
\text{restaurant\ meals}=0
\text{beverage}=\text{tap water}
\text{cooking\ skill}=\text{high}

  • Raises realism question & implications for SNAP allotments.

Time & Convenience Constraints (Pages 28–30)

  • Cash transfers alone (e.g., SNAP) may underperform if time scarcity is dominant barrier.
    • Low-income individuals often juggle multiple jobs → limited cooking time.
    • Perceived time pressure correlates with poorer diet quality (Beshara 2010,Welch, Welch2009).
  • Convenience defined: minimization of time/effort in acquiring, preparing, consuming food.
    • Solutions: 24-hr stores, online grocery, meal kits, self-checkout.
  • Case comparison: Take-out veggie wrap vs. homemade
    • Dimensions: prep time, acquisition time, portability, cleanup, ease of eating.
    • Even if homemade is cheaper/nutritionally superior, convenience premium may drive purchase of take-out.

Integrative Takeaways

  • Food choice is a multidimensional optimization of {\text{taste},\, \text{price},\, \text{nutrition},\, \text{convenience},\, \text{culture}}underpersonalconstraintsunder personal constraints{\text{income},\, \text{time},\, \text{skill}}$$.
  • Economic analyses confirm systematic tendency for energy-dense, nutrient-poor foods to be cheapest per kcal; yet cost-effective, nutrient-dense items do exist.
  • Policy instruments must jointly consider money and time (e.g., healthy ready-to-eat subsidies, culinary education, workplace scheduling flexibility).
  • Ultimately, improving diet quality among low-income populations requires aligning healthful options with affordability and convenience while respecting cultural foodways.