Tag: Knowledge recall

The evidence is mixed but suggestive. Gearhardt’s 2011 imaging study found reward-region activation patterns paralleling those seen in substance dependence, in 39 young women, with the group contrast resting on 15 participants against 11. Some people show addiction patterns: craving, loss of control, continued use despite consequences. Whether this constitutes clinical “addiction” is debated; the parallels are measured, but what they mean is not settled. The label matters less than the pattern. This companion covers the case for and against food addiction, and practical implications. (3 min read)

The energy balance equation is physics: it must be true. But it’s incomplete, because “calories in” and “calories out” aren’t independent variables. Hall’s modeling work shows expenditure adapts to intake, so both terms move at once; the familiar “3,500 calories equals a pound” rule treats expenditure as fixed and so underestimates the body’s response, which is why plateaus arrive early. Eating less is met with lower resting expenditure, rising ghrelin, and muscle that extracts more work per calorie, so a formerly obese person needs roughly 300-400 fewer calories a day than someone who was never obese. Across 29 long-term studies,…

One model has the body defending a weight setpoint like a thermostat defends temperature, one of three and not settled. Leibel and Rosenbaum found that when you eat less, the body reduces expenditure and increases hunger, pushing back toward the weight it started from. This is one reason dieting alone often fails: you’re fighting regulatory systems. Whether fasting, food quality, and time can change what the body defends is proposed rather than shown. This companion covers the thermostat model and its limits, the evidence, why the defended weight may be elevated, and how to change it. (4 min read)

Hunger isn’t purely about need: it’s entrained to your circadian clock. Cummings’s 2001 study found ghrelin rising nearly twofold before meals, which its authors read as suggesting a role in starting them. You can feel hungry at noon even after a late breakfast, partly because that’s when you usually eat. Patterns appear to shift with consistently new meal times, though how quickly is unsettled: in one study ghrelin’s daily rhythm was still intact after more than three days without food. This companion covers circadian control, the anticipatory rise, evidence for timing over need, and practical implications. (3 min read)

Fasting is widely reported to get easier with practice, and no study has followed anyone across repeated fasts to find out. Multiple systems adapt, though not the way it is usually told. Ghrelin keeps spiking at your customary meal times even while you fast, which its authors read as support for the brain setting the timing, while overall levels fall, so the waves keep their schedule and arrive smaller. Psychological tolerance is reported to build as people learn hunger waves pass. The fat-adaptation account comes from low-carbohydrate diet research in athletes rather than from studies of fasting. This companion covers…

Acute stress typically suppresses appetite: fight-or-flight prioritizes survival over digestion. Chronic stress often has the opposite effect. Elevated cortisol is proposed to increase appetite, especially for calorie-dense foods, and in one lab study high cortisol reactors ate more after a stressor and preferentially chose sweet foods. Two further steps are proposals rather than demonstrated mechanisms: that comfort eating then quiets the stress response, and that cortisol builds the fat around your organs, though the study behind that compared women who already differed in shape, so it cannot say which way the arrow runs. Short-term crises can make eating difficult; long-term…

Repeated dieting can make future weight loss harder. Research by Fothergill on “Biggest Loser” contestants showed severely suppressed metabolic rates years later. The body adapts through reduced metabolism, increased hunger hormones, and, on the usual account, more efficient fat storage. Each yo-yo cycle may strengthen these defenses, on an account its authors call a proposal awaiting discovery. Short-term fasting does not lower metabolic rate the way continuous restriction does. This companion covers the body’s defense systems, the yo-yo effect, why fasting may differ, and the practical implications. (4 min read)

During fasting, the body excretes more sodium, and potassium with it. Controlled studies put the sodium shortfall at roughly 30-40 mmol a day over the first few days, when the drop in insulin is steepest, and insulin is what drives both. Magnesium is the least settled of the three: the claim that it is lost too comes from low-carb diet guidance. Symptoms people blame on “not eating” are often put down to low electrolytes, though no study has tied them to measured loss. Depletion accumulates over days, so a short fast costs a fraction of what a multi-day one does;…

Fasting tends to produce recognizable stages: initial hunger that often fades, a stable period as fuel sources shift, meal-time ghrelin waves, then a widely reported sense of clarity as ketones rise. Research on ghrelin shows it peaks and falls at habitual meal times even without food, in a six-person fasting study that measured the hormone rather than hunger. Waiting out a wave is often reported to bring relief. This companion covers the early hours, the transition, meal-time waves, the metabolic shift, which begins from about 12 hours, and what to expect with practice. (4 min read)

Some people process carbohydrates efficiently; others spike sharply from the same foods. A study of 800 people found high variability between people’s responses to the same meals. Factors include blood measures, dietary habits, body measurements, physical activity, and gut microbes, and the authors attribute much of the variation to factors you can change. This companion covers why variation exists, factors affecting tolerance, whether it can change, and practical implications. (3 min read)