Hidden Sugar: Why Starch Acts Like Sugar — and How to Lower Your Glycemic Load
Starch behaves like sugar in the body: how much blood sugar hides in rice, bread & bananas, what glycemic load means — and how type 2 diabetes can often be reversed.
A few decades ago, type 2 diabetes was the "old-age sugar disease." Today clinics see it in under-25s. While life expectancy in the West stagnates, the healthspan — the years free of chronic disease — is shrinking. UK family doctor Dr. David Unwin calls it a quiet pandemic of poor metabolic health.
His central, surprisingly simple observation: much of this "hidden sugar" isn't in the candy aisle but in foods we think are harmless — rice, bread, potatoes. And for many people, the damage can be reversed. But if starch is the problem — what do you put on the plate instead? That's exactly what we'll settle.
What the evidence supports
| Claim | Evidence | Reality check |
|---|---|---|
| High glycemic load drives blood sugar & insulin | 🟢 strong | Well established — the basis of the whole topic |
| Type 2 diabetes is reversible for many | 🟢 strong | RCTs (DiRECT) show remission, mainly via weight loss |
| Teaspoon visualisation as a learning aid | 🟡 useful | A didactic blood-sugar equivalent, not actual sugar content |
| Hyperinsulinemia ↔ cancer risk | 🟠 emerging | Associative; plausible mechanisms, no causal chain for the individual |
| Fructose as a "building block" for tumors | 🟠 emerging | Promising, mostly preclinical data |
| "Depleted soils" make Mg deficiency an epidemic | 🔴 overstated | Magnesium is often marginal — the soil story is wellness folklore |
"Starch is sugar holding hands"
The core misunderstanding is about starch. Starchy carbohydrates — bread, pasta, rice, potatoes — are biochemically nothing but long chains of glucose molecules holding hands. The moment they meet our digestive enzymes (amylase, already in saliva), the bonds break and the body is flooded with glucose — much like a spoon of sugar.
To make this tangible, Unwin translates the glycemic load (how much a given portion raises blood sugar) into teaspoon equivalents (1 teaspoon ≈ 4 g).
| Food (typical portion) | Blood-sugar equivalent (4 g teaspoons) |
|---|---|
| 150 g cooked white rice | ≈ 10 |
| Large baked potato | ≈ 9 |
| 1 bowl of cornflakes (unsweetened) | ≈ 8 |
| Standard chocolate bar | ≈ 7.5 |
| 1 large ripe banana | ≈ 6 |
| 1 small slice of wholegrain bread | ≈ 3 |
Important: These teaspoons are a blood-sugar equivalent based on glycemic load — not actual sugar content. Rice doesn't contain 40 g of sugar; it just acts in the blood like that amount. As a teaching tool it's powerful; don't confuse it with a lab value.
For comparison: the entire bloodstream (~5 litres) holds, in a healthy state, roughly a single teaspoon of dissolved sugar. In strongly insulin-resistant people, a ripe banana can raise blood sugar substantially.
How metabolism quietly derails
Briefly, because the mechanism is covered in depth in Keto, insulin resistance & the aging brain: excess glucose is converted to fat and stored — among other places — in the liver (fatty liver/NAFLD). The fatty liver impairs insulin's action → insulin resistance. The pancreas pumps out ever more insulin to compensate — often unnoticed for over a decade (Roy Taylor: the "long, silent scream of the liver"). When insulin production finally collapses, type 2 diabetes manifests.
You won't catch your status from standard blood glucose alone, but via fasting insulin + fasting glucose → HOMA-IR — more in Bloodwork & biomarkers.
What replaces the calories?
The most important practical question — and where most "less sugar" advice falls apart. If you cut starch and sugar, don't fill the gap with hunger, but with substance:
| Reduce (high GL) | Replace with |
|---|---|
| White flour, white rice, cornflakes, sweets, juices | Protein at every meal (eggs, fish, meat, legumes, quark) |
| Large amounts of potatoes/pasta | Healthy fats: olive oil, nuts, avocado, oily fish, full-fat dairy |
| Sugar-sweetened drinks | Fibrous vegetables to fullness — barely move blood sugar |
Reality check — not a war on all carbs: This is about glycemic load, not "carbs are evil." Complex, intact low-GL carbohydrates — legumes, intact whole grains (lentils, beans, oats) — are valuable for most people (fibre, micronutrients, satiety) and belong in any sensible diet. Low-carb is one lever, not a mandate to go keto. Someone with no diabetes risk who trains hard tolerates far more starch than someone with a fatty liver.
The real payoff: protein and fat keep you full, blood sugar stays flat — and the hunger rollercoaster from constant blood-sugar spikes disappears.
Sugar, insulin & cancer — carefully framed
The consequences of chronically high blood sugar and insulin (hyperinsulinemia) reach beyond diabetes and cardiovascular disease. There are associations with several cancers — but beware causal shortcuts:
- High insulin/IGF-1 is associated with suppressed apoptosis (programmed cell death) and cell growth — a plausible mechanism, not a guarantee in any individual.
- Fructose can promote tumor growth in preclinical models (the liver converts it to lipids) — emerging, not settled.
- Sugar-sweetened drinks are associated with higher cancer risk (NutriNet-Santé: ~18% relatively higher overall-cancer risk from ~100 ml/day — on a modest baseline) and with shorter telomeres (Leung 2014).
Deeper on the metabolism-cancer question: Cancer as a metabolic disease (Warburg/Seyfried).
Why discipline alone isn't enough
Poor eating isn't purely a willpower problem. Clinical psychologist Dr. Jen Unwin notes that a substantial share of people show addiction-like symptoms toward ultra-processed foods — products engineered for the "bliss point" that maximally triggers the reward system (Yale Food Addiction Scale).
Pure banning or "policing" usually leads to secrecy and shame, per behavioural research. What works better is honesty with yourself — and, for genuine trigger foods, often abstinence rather than "just a little," much like nicotine.
The GRIN model for lasting change
- G — Goals: Picture a concrete, positive future ("still hiking with the grandkids at 70").
- R — Resources: What strengths, experiences, supportive people do you already have?
- I — Increments: What tiny, realistic change can you make today?
- N — Notice: Reflect in the evening: what went well? How do more energy and less brain fog feel?
The string test: a 30-second self-check
A surprisingly good indicator of concerning visceral fat is the waist-to-height ratio (target: waist < half your height):
Take a string the length of your height and fold it once in the middle. The half-string should pass comfortably around the widest part of your belly. If it won't reach around, that's a warning sign of elevated insulin-resistance risk.
A note on magnesium: a marginal magnesium status really is common and affects sleep, muscles and nerves — but the popular "depleted soils" story is overstated. If you supplement, well-tolerated magnesium glycinate usually beats high-dose citrate (which tends to be laxative). Want to replace sweetness entirely rather than just swap it? See sugar alternatives compared.
Bottom line
- Starch acts like sugar in the blood — the biggest "hidden sugar" is in bread, rice and potatoes, not just sweets.
- The teaspoon table is a powerful learning tool (glycemic load), not a lab value.
- Fill the gap with protein, healthy fats and fibrous vegetables — plus the right, complex carbs (legumes, intact whole grains). It's not a war on all carbs.
- Metabolic damage is often reversible — measure your HOMA-IR, do the string test, and change in small steps (GRIN).
- [1]Dr. David Unwin on *The Diary of a CEO* (basis & starting point for this piece)
- [2]Unwin et al.: low-carb approach & type 2 diabetes remission in primary care — BMJ Nutrition, Prevention & Health
- [3]DiRECT trial (Lean, Taylor et al. 2018): diabetes remission via weight loss — Lancet (RCT)
- [4]Chazelas et al. (2019): sugary drinks & cancer risk (NutriNet-Santé) — BMJ
- [5]Leung et al. (2014): sugar-sweetened beverages & telomere length
- [6]Gearhardt et al.: ultra-processed foods & addictive-like eating (Yale Food Addiction Scale)
- [7]The Public Health Collaboration (PHC): sugar-equivalent infographics (Dr. David Unwin)
