Chapter 11: Risks, Side Effects and Who Should Talk to a Doctor First
Summary: Keto is a real change to how your body runs, so it carries risks like any other intervention; most of them are manageable if you know your starting point, involve your doctor when you have a health condition or take medication, and follow up on symptoms instead of guessing.
On this page
- The short answer
- Keto is an intervention, and so is doing nothing
- Who should talk to a doctor first
- Baseline labs: know your starting point
- Medication: why doses can change
- Cholesterol and blood lipids
- Common side effects
- Eating-disorder history
- What the evidence does and does not cover
- Related
The short answer
- Talk to your doctor before you start if you take medication for diabetes or blood pressure, have type 2 diabetes or pre-diabetes, have kidney or heart history, are pregnant or breastfeeding, or have a history of an eating disorder.
- Get baseline labs (blood sugar, lipids, kidney function) before you start, so you have something to compare with later.
- Expect lipid changes. Low-carb diets tend to lower triglycerides and raise HDL, but the effect on LDL varies from person to person (National Lipid Association, 2019).
- Most early side effects (tiredness, headaches, cramps, constipation, poor sleep) trace back to lost water and salt, low fibre, or the switch away from carbs. They usually have a simple fix.
- Some symptoms are a doctor visit, not a forum question. See Common Keto Side Effects.
KetoDick on this: his videos routinely open with a disclaimer that he is not a doctor or dietitian (video UygKGoP_BtA; video uXzscHudgt0), and he names specific cases where a doctor should be involved (video GojQvo_2GS0; video UygKGoP_BtA).
Keto is an intervention, and so is doing nothing
Any big change in diet affects blood sugar, blood fats, fluid balance and appetite. That is why it works, and it is also why it can cause problems for some people.
The fair comparison is not keto against perfect health. It is keto against the way you eat now. A diet that keeps you gaining weight or keeps your blood sugar climbing has its own risks.
Medical groups do not treat low-carb eating as fringe. The American Diabetes Association lists low-carbohydrate patterns as one of several acceptable options for adults with diabetes or pre-diabetes when the plan is individualised (ADA, Evert et al., 2019; ADA Standards of Care, 2025). The ADA and European diabetes group list it among nutrition approaches for weight and blood sugar (Davies et al., 2022).
"Acceptable when individualised" means a plan built around you, with your care team watching the numbers.
KetoDick on this: he compares keto to surgery: risky, sometimes worth it, and not necessarily permanent. He asks whether a standard diet of about 250 g of carbs a day is not also dangerous, and says that not changing your diet is a risk too (video 1m1hPgaRIg4; video uXzscHudgt0).
Who should talk to a doctor first
Some people should involve a doctor before they start, not after a problem shows up.
| Your situation | Why it matters on keto | Details |
|---|---|---|
| Diabetes medication (especially insulin) | Cutting carbs lowers blood sugar, so the dose you take now may become too much | Medications |
| Blood-pressure medication | Keto changes fluid and salt balance, and blood pressure can shift | Medications |
| Type 2 diabetes or pre-diabetes | Blood sugar and ketone readings mean different things for you | Ketoacidosis vs ketosis |
| Kidney disease or kidney risk | Electrolyte supplements and protein targets need a doctor's input | Protein and kidneys |
| Heart history or high cholesterol | LDL can rise in some people | Cholesterol |
| Pregnancy or breastfeeding | None of the studies cited in this guide looked at this group | Who should talk to a doctor |
| Eating-disorder history | Strict food rules and fast-result chasing can feed old patterns | Eating disorders |
The full list, with the reasons for each case, is in Who Should Talk to a Doctor Before Starting Keto.
Baseline labs: know your starting point
A baseline is a set of lab results taken before you change anything. Without it, you cannot tell whether a later number went up, went down or stayed the same.
Common baseline tests to ask about:
- Fasting blood sugar and HbA1c (average blood sugar over about three months).
- A lipid panel: total cholesterol, LDL, HDL and triglycerides.
- Kidney function and electrolytes (sodium, potassium).
- Blood pressure, measured at the office or at home.
Repeat them after a few months on the diet and compare. Your doctor decides which tests fit your history.
KetoDick on this: he tells older viewers and anyone with health history to get baseline values from a doctor, so they can compare at 6 to 12 months (video GojQvo_2GS0). He also suggests asking for a lipid test even if you are young, and checking that insurance covers it first (video cTGYIFOTPl8).
Medication: why doses can change
Diabetes and blood-pressure medicines are dosed for the way you eat now. When you cut carbs sharply, blood sugar can fall and fluid balance can shift within days.
In one non-randomised clinic study of adults with type 2 diabetes, the low-carb group's HbA1c fell from 7.6% to 6.3% and they used less diabetes medication than the usual-care group (Hallberg et al., 2018). In that study the medication changes were made by the care team. Doing it yourself is how people get into trouble.
More in Keto With Diabetes or Blood-Pressure Medication.
KetoDick on this: he tells anyone with a condition or on medication to review his advice with their doctor, "especially" the dosing (from the video; video UygKGoP_BtA).
Cholesterol and blood lipids
The National Lipid Association's 2019 statement says low- and very-low-carb diets lower triglycerides and raise HDL ("good") cholesterol, with a variable effect on LDL (Kirkpatrick et al., 2019). A meta-analysis of 13 trials lasting 12 months or more found higher HDL and higher LDL on very-low-carb diets compared with low-fat diets (Bueno et al., 2013).
So LDL rising is a known pattern for some people, not a rumour. A lipid panel before and after is the only way to know which group you are in.
KetoDick on this: he says cholesterol may spike at the first reading and then improve over 6 to 12 months, and credits most cardiovascular improvement to weight loss (video UygKGoP_BtA). The trials above report LDL rising on average over 12 months or more, so his "improves later" view and the meta-analysis do not fully match. Details in Cholesterol on Keto.
Common side effects
| Side effect | Usual cause | Simple first step |
|---|---|---|
| Tiredness, headache, "keto flu" | Water and salt loss in the first weeks; adapting to less carb | Salt, broth, enough fluid; see Keto flu |
| Leg cramps | Low sodium, potassium or magnesium | Check salt and leafy greens; see Potassium and magnesium |
| Constipation or loose stools | Less fibre; gut bacteria adjusting | Add low-carb vegetables |
| Poor sleep | Early adaptation; electrolytes | Usually passes in a few weeks |
| Bad breath, body-odour changes | Ketones | Usually harmless |
Palpitations, fainting, chest pain, swelling, or symptoms that do not ease after the first month are a doctor visit. The full list is in Common Keto Side Effects.
KetoDick on this: he says to watch for cramping, trouble sleeping or "something weird like sweats" (from the video) and follow them up with a doctor instead of a forum (video 1m1hPgaRIg4).
Eating-disorder history
Keto has strict rules, fast early scale drops, and a social-media culture of before-and-after photos. For someone with a history of restriction or bingeing, that mix can be risky.
If that is you, plan keto with your therapist and your doctor, or choose a less rigid approach. See Keto and Eating-Disorder History.
KetoDick on this: he says anyone with an eating disorder should talk to "at least your therapist and probably also your doctor" before doing keto (from the video; video xyEZL0HuejI), and warns that the race for posted results pushes some people toward anorexia (video 7Aixw4uRksI).
What the evidence does and does not cover
- Who was studied: most of the keto and low-carb trials cited in this guide enrolled adults with overweight or obesity, and none of them studied pregnancy. Results may not carry over to other groups.
- How long: the NLA statement found low-carb diets were not better than other diets for long-term weight loss, though they may give more loss in the short term (Kirkpatrick et al., 2019).
- Kidneys: in adults without kidney disease, higher protein intakes did not change kidney filtration differently from lower ones (Devries et al., 2018). That finding does not apply if you already have kidney disease.
- Ketosis vs ketoacidosis: nutritional ketosis and diabetic ketoacidosis are different states (StatPearls, Masood et al.). See Ketoacidosis.
KetoDick on this: he warns against confirmation bias: a keto forum will answer every question with "keto," and the diet may not suit everyone's genetics or gut (video 1m1hPgaRIg4).
Related
In this chapter
- Who Should Talk to a Doctor Before Starting Keto
- Keto With Diabetes or Blood-Pressure Medication
- Cholesterol on Keto
- Common Keto Side Effects
- Keto and Eating-Disorder History
Guide
Blog
- Is keto dangerous?
- Blood tests to get before keto
- How to talk to your doctor about keto
- What the ADA says about low-carb diets
- Does keto cause kidney stones?
- Saturated fat on keto
- Keto forums and confirmation bias
Videos
- Keto is DANGEROUS and warnings from friends
- Are dark keto test strips dangerous?
- Making sense of electrolytes
- Keto basics for beginners
- Beginner keto questions and tips by a random guy
Previous: Chapter 10: Maintenance · Next: Chapter 12: Nutrition Science · Guide contents
Last verified: 2026-10-31