What are Zone and Keto?
Zone diet: a balanced pattern targeting roughly 40% carbs / 30% protein / 30% fat (often framed as “40-30-30”).1
Ketogenic diet (“Keto”): very low carbohydrate (often <10%–15% of calories) and high fat to promote nutritional ketosis.
What the evidence says
- Weight loss: In a 12-month head-to-head RCT of popular diets, Atkins (very low carb) beat Zone for weight loss; both were modest overall. Large trials show that low-fat vs. low-carb plans produce similar 12-month losses when both emphasize quality and a calorie deficit—adherence is the main driver.2, 3, 4, 5
- Cardiometabolic markers: Meta-analyses suggest low-carb patterns often improve triglycerides (↓) and HDL (↑) more than low-fat, while low-fat tends to reduce LDL-C more. Some ketogenic trials report LDL-C increases, especially in normal-weight adults or with higher saturated fat.6, 7, 8, 9
- Performance & early “water-weight” changes: Low glycogen at Keto start can drop scale weight quickly (each gram of glycogen stores ~3 g water). For endurance, some elite data show impaired exercise economy on ketogenic diets; overall, performance effects are mixed and sport-specific.10, 11
Scorecard
| Outcome | Zone | Keto |
|---|---|---|
| Weight loss (12 mo) | Modest; similar to other balanced plans when calories controlled. | Modest on average; sometimes faster early losses (water + fat).2, 3 |
| Triglycerides / HDL | Improves with weight loss/quality carbs. | Often more favorable (TG↓, HDL↑).6 |
| LDL-C | Often decreases with lower saturated fat. | Can increase in some; use unsaturated fats and monitor labs.7, 8, 9 |
| Athletic performance | Compatible with mixed training. | Mixed; some elite data show reduced exercise economy.11 |
| Ease & sustainability | Higher—more food flexibility, easier dining out. | Lower for many—more restrictive and social frictions. |
Who might choose which?
- Consider Zone if you want flexibility, eat with family often, or prefer balanced plates without tracking every gram.
- Consider Keto if you’re motivated by structure, like rich (unsaturated-fat) foods, and are ready to monitor lipids with your clinician. If LDL-C rises, adjust fats (olive oil, nuts, fish) or pivot to a less restrictive low-carb plan.9
- Medical caveats: Very-low-carb/keto approaches may be inappropriate for certain conditions (e.g., type 1 diabetes, some liver/kidney disease, pregnancy). Always individualize with your healthcare team.12, 13
Whichever route you choose, the big rocks are: a steady calorie deficit, adequate protein (≈25–40 g/meal), and fiber from veggies/fruit/legumes. For practical help, see calorie targets, high-protein basics, foods that keep you full, and portions vs. counting. If Keto stalls, read why you’re not losing on keto. Prefer done-for-you? Browse our calorie-controlled meal plans.
How to build plates (examples)
Zone-style day (≈40/30/30)
- Breakfast: Greek yogurt bowl + berries + 1 Tbsp almonds.
- Lunch: Chicken, quinoa, roasted peppers/onions, salsa + lime yogurt.
- Dinner: Salmon, brown rice, broccoli, olive-oil vinaigrette.
- Snack: Hummus + carrots/celery or cottage cheese + fruit.
Keto-compatible day (≤10–15% carbs; focus on unsaturated fats)
- Breakfast: Eggs with spinach/mushrooms; side avocado (measured).
- Lunch: Big salad (olive oil, vinegar), salmon or chicken thighs, olives, seeds.
- Dinner: Bunless turkey burger, zucchini “fries” (air-fried), slaw with olive-oil mayo.
- Snack: Greek yogurt (low-sugar) or cheese + cucumbers.
Training hard? Remember that early Keto losses include glycogen+water; if performance matters, a less restrictive low-carb or Zone-style plan may feel better. Post-workout carbs guide.
FAQs
Which diet is better for lowering triglycerides?
Low-carb/keto patterns often lower triglycerides more than low-fat, but LDL may rise in some—favor unsaturated fats and monitor labs.6, 7
Why do I lose weight fast the first week on Keto?
Depleting glycogen also sheds water (≈3 g water per gram of glycogen), so the scale drops quickly at first.10
Can I mix elements of both?
Yes—many people do best on a moderately low-carb plan emphasizing protein, produce, whole-food fats, and calorie control.
References
- “Zone Diet” overview (40/30/30). sciencedirect.com.
- A TO Z RCT: Atkins vs Zone vs LEARN vs Ornish (12 months). PubMed · JAMA.
- DIETFITS RCT: healthy low-fat vs healthy low-carb—no 12-mo difference when quality emphasized. JAMA (PMCID).
- NEJM macronutrient RCT (811 adults): similar weight loss across fat/protein/carb targets when calories controlled. NEJM.
- Popular diets review: Atkins/WW/Zone show modest, similar long-term weight loss. AHA journal.
- Low-carb vs low-fat meta-analysis: TG↓/HDL↑ on low-carb; LDL/TC drop more on low-fat. Frontiers in Nutrition.
- Randomized feeding trial: ketogenic diet increased LDL-C in healthy young women. AJCN.
- Meta-analysis: ketogenic diets raised LDL-C/TC in normal-weight adults (results varied for TG). PubMed.
- AHA guidance: keep saturated fat low to manage LDL-C. AHA statement · heart.org.
- Glycogen binds ~3 g water per gram (explains early “water weight”). Sports Med Open.
- Elite endurance data: ketogenic diet impaired exercise economy/performance. J Physiol (reviewed) · PLOS One.
- ADA Standards: many patterns can work—individualize; reduce overall carbs to improve glycemia in diabetes. professional.diabetes.org · 2024 PDF.
- Review of reported contraindications to ketogenic diets (context). Endocrinol Diabetes Metab.
Educational content only; not medical advice.
