Compared to What? The Question That Changes How You Eat

Most food advice arrives as a verdict: this food is good, that one is bad. But no one eats a food in isolation. Every time you add something to a meal, something else is displaced. The more honest question is rarely "is this food healthy?" — it is "compared to what?" [2] Hold that question for a moment, because it quietly dismantles a lot of nutrition noise.

There is a tidy mental model of nutrition that works like rock, paper, scissors: one food beats another, the losing food gets cut, and you win. A recent discussion on Sigma Nutrition Radio argues this is precisely the wrong way to read the evidence [2]. When researchers want to understand the health effect of eating more or less of something, they often use what are called food substitution models. The logic is simple: increasing one food usually means decreasing another, so the relevant comparison is not "food X versus nothing" but "food X versus whatever it replaces" [2].

The problem is how these models get communicated. A finding that, say, swapping one food for another is associated with better outcomes gets flattened into "this food is bad, remove it." That is a misinterpretation [2]. The model never said the food must be eliminated — only that, in a given comparison, one option fared better than another. The substitution is the whole point. Strip it away and you are left with a moral ranking the data never supported.

This matters because it reframes one of the most contested topics in nutrition: unprocessed red meat and cancer. Another Sigma episode makes the case that the evidence here is routinely presented in overly simplistic terms [3]. The useful questions, the discussion argues, are narrow and specific: does the evidence identify intake levels at which colorectal cancer risk rises, and do controlled human trials support a plausible mechanism for that risk? [3] Those are harder questions than "is red meat bad," and they resist a yes/no answer.

The episode also pushes back on a popular reassurance — that fibre, vegetables, or an otherwise "healthy diet" can neutralise a high red meat intake. Whether that claim is actually supported by the mechanistic evidence is, the discussion suggests, far from settled [3]. This is worth sitting with, because it cuts against the comfortable instinct to offset rather than reconsider. "I eat lots of vegetables, so the rest evens out" is a substitution argument too — and it deserves the same scrutiny as any other.

Notice what connects these two pieces. Both reject the rock-paper-scissors instinct in favour of asking what is actually being compared, at what dose, through what mechanism. That is the difference between nutrition as a value system and nutrition as a question.

The same discipline applies to supplements, where marketing thrives on the opposite logic — one product to beat all others. A recent systematic review and network meta-analysis compared dietary protein, creatine, and omega-3 supplementation for muscle strength, endurance, and recovery in trained athletes [5]. The study restricted itself to randomised controlled trials in people doing structured training for at least six months, and used network meta-analysis to weigh these supplements against one another rather than each in isolation [5]. That design is itself a substitution model in spirit: not "does creatine work?" but "how does it compare, head to head, with the alternatives?" The honest takeaway is that these three do different jobs, and ranking them only makes sense once you specify the outcome you care about.

There is one population for whom the "compared to what" problem runs deeper still: women. A narrative review in Strength and Conditioning Journal points out that many dietary and nutrient recommendations rest on research conducted only in men [1]. Yet the physiological, neurological, and hormonal changes across a woman's life cycle meaningfully alter nutritional needs — and current frameworks largely lack sex-specific guidelines [1]. So when a woman is told what to eat for performance, the unspoken comparison is often "compared to a man," which is not a comparison that holds.

The parallel shows up in training, too. A 2026 article on prejudice in women's resistance training notes that women face distinct challenges in bone development and loss, driven by estrogen's role, which leaves lower peak bone mass and higher fracture risk — especially after menopause [4]. Resistance training is an effective way to protect bone health, yet misconceptions about excessive muscle gain and "loss of femininity" still deter many women from it [4]. Here the substitution question turns personal: what are you giving up by not lifting? The evidence suggests the answer is bone.

RESEARCH RADAR

• Substitution, not subtraction. Food substitution models are useful for estimating the effect of eating more or less of something, but they are frequently miscommunicated as a contest where the "losing" food must be removed entirely [2]. The comparison is the finding — not a verdict on any single food.
• Red meat questions need precision. The debate over unprocessed red meat and cancer turns on specific thresholds of intake and plausible mechanisms, not a vague "balanced" stance; whether a healthy diet can offset high intake is not clearly supported [3].
• Guidelines built on men. A recent review highlights that calorie, carbohydrate, fat, protein, and supplement recommendations are largely derived from male subjects, despite women's needs shifting across the life cycle — and sex-specific guidelines are largely absent [1].

ONE THING TO TRY

Next time you label a food as one to "avoid," finish the sentence: avoid it in favour of what? Name the actual replacement. If you can't, the verdict may be doing less work than the comparison would [2].

WORTH YOUR ATTENTION

• Rock, Paper, Salmon — Sigma Nutrition Radio #610 — the clearest explanation of why "compared to what" should anchor how you read food research [2]. https://sigmanutrition.com/podcast/episode610/
• Unprocessed Red Meat & Cancer Risk — Sigma Nutrition Radio #609 — a careful, non-tribal walk through one of nutrition's most flattened debates [3]. https://sigmanutrition.com/podcast/episode609/
• Strength unseen — Annals of Medicine — on bone health, estrogen, and the misconceptions keeping women out of resistance training [4]. https://doi.org/10.1080/07853890.2026.2661150
• Protein, creatine, omega-3 head-to-head — Nutrients — a network meta-analysis that compares supplements rather than hyping any one [5]. https://doi.org/10.3390/nu18060909

The quiet lesson across all of this is that good nutrition is less about verdicts and more about comparisons made honestly. "Compared to what?" is not a hedge — it is the most demanding question you can ask of your own habits, because it refuses to let any choice float free of its alternative [2]. Ask it gently, and most of the guilt falls away with the false certainty.