Nutrition

Diet, specific nutrients, and their effects on brain function and mood.

Applied Science Survey

SP-8Nutrition and Eating BehaviorSeparating dietary signal from noise: evidence on dietary patterns, macronutrients, meal timing, ultra-processed foods, and behavioral strategies for dietary change. Covers PREDIMED, DASH, intermittent fasting, and food environment effects.Read survey →

Research synthesis2 min read

What the Nutrition Research Actually Shows

Nutrition research is plagued by confounds, but some findings are robust. Here's what holds up under rigorous scrutiny — and what's mostly noise.

Why Nutrition Research Is Hard

Dietary studies face a methodological mountain: you can't blind people to what they eat, recall data is unreliable, diet and lifestyle co-vary, and most important outcomes (cardiovascular disease, cognitive decline) take decades. The majority of nutrition headlines come from observational studies with uncontrolled confounders. When the RCT evidence is examined separately, it's considerably thinner.

What Replicates Strongly

Caloric balance determines body weight with high consistency. Despite complexity in metabolic adaptation, total energy intake versus expenditure predicts body weight change across populations and intervention types. Metabolic ward studies show this with high precision. Where diets differ dramatically — low-carb vs low-fat — the long-term weight differences largely disappear when calories and protein are matched.

Protein is the most satiating macronutrient and has the highest thermic effect. High-protein diets (1.6–2.2g/kg) consistently produce greater fat loss than isocaloric lower-protein diets in RCTs, primarily through satiety and diet-induced thermogenesis. This effect holds across dietary patterns — it's macronutrient-level, not food-source-level.

Dietary fibre is causally linked to improved gut microbiome diversity and lower CVD risk. The PREDIMED trial and others demonstrate fibre's protective role via multiple mechanisms (microbiome, glucose regulation, satiety). Most people consume less than half the recommended 30g/day. This is one of the highest-confidence actionable findings in nutrition epidemiology.

Ultra-processed food consumption predicts poorer health outcomes independent of macronutrient content. Kevin Hall's 2019 randomised crossover trial — the first to directly compare ultra-processed vs unprocessed diets with matched macros — found spontaneous caloric overconsumption of ~500 kcal/day on ultra-processed diets. Mechanism: food reward engineering, faster eating rate, reduced satiety signalling.

Omega-3 fatty acids (EPA+DHA) reduce systemic inflammation. Marine omega-3 RCTs consistently show reductions in inflammatory markers (CRP, IL-6). Cardiovascular benefit is clearer in high-risk populations; cognitive benefit requires longer study durations. Dose threshold for anti-inflammatory effects: approximately 1g EPA+DHA/day.

What the Research Can't Tell You

Individual glycaemic response to identical foods varies ~2–3× between people (Weizmann Institute CGM studies). The "best diet" in population averages may be poor for you individually. Tracking your own glucose, energy, and satiety response to specific meals is more informative than applying dietary patterns designed for groups. The meal quality signals worth monitoring personally are energy stability, satiety duration, and sleep — not just weight.

Full article →Test this on yourself →

Evidence caution

Most nutrition research relies on self-reported dietary recall, which has poor validity. Single-food claims rarely survive rigorous controlled trials.

Evidence base

Min quality:

50 papers

RCTWikiHigh evidence score

Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient

Stephen A. McClave, Beth Taylor, Robert G. Martindale +13 more · Journal of Parenteral and Enteral Nutrition · 2016 · 3,888 citations

This clinical practice guideline from the American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) and the Society of Critical Care Medicine (SCCM) synthesises evidence from over 200 randomised controlled trials to recommend that critically ill patients should receive early enteral nutrition (within 24–48 hours of ICU admission) rather than parenteral nutrition, with specific protein targets of 1.2–2.0 g/kg/day, and that trophic feeding (low-volume) is acceptable for the first week in patients with medical contraindications to full feeding — but the evidence is weak for most recommendations, with GRADE quality ratings of "very low" to "moderate" across nearly all outcomes.