Exercise on Keto: What Beginners Should Do, and When Carbs Around a Workout Make Sense
In this recording
A 50-minute Facebook Live from April 2019, sitting by a fire. I promised to keep it short. I didn't.
- [0:00] The usual opener: I'm not qualified, this is information, check with your trainer and your doctor.
- [0:40] The plan in four parts: what beginners should do, the advantages of ketosis for exercise, the disadvantages, and the biology.
- [1:58] For most people: light resistance work, light muscle engagement, light cardio. A 30-minute walk counts.
- [3:22] Body-weight squats, push-ups and planks, scaled to a wall or a counter if the floor is too much. Work around bad joints.
- [5:23] Light to moderate exercise twice a week helps the heart, lungs and blood pressure for people who haven't been active.
- [8:59] I don't recommend starting exercise during the introductory month unless it's already your routine.
- [9:21] Cramping, low energy and light-headedness are three signs your electrolytes are off. Broth with a little potassium salt is the easy fix.
- [10:30] The advantages: muscle glycogen is the explosive fuel, but body fat is a far bigger tank for long endurance work.
- [13:10] Small, measured doses of sugar around hard training, and my guess that ketone drinks could one day be treated like doping.
- [17:05] The disadvantages: glycogen sits inside the muscle, so explosive work will always favour some glucose.
- [23:31] The biology: insulin, lipase, the three ketone bodies, and how long it takes to lose metabolic flexibility.
- [29:48] Grandma's carrot cake: don't worry about it, and don't turn it into a habit of eating and then "paying it back".
- [33:40] A viewer asked about plain water. My answer: start with small, equal amounts of sodium and potassium in a litre of water.
- [43:31] The last few minutes switch topics. They preview a separate broadcast on keeping your email and tax documents safe from hackers. This post doesn't cover it.
Watching this in 2026
The first ten minutes are the part to keep. For someone who hasn't moved in years, I said the goal is to be active at all: walk, take the stairs, hold a plank against the counter (live TFCK5340). I also said, more than once, to work around your own body. Bum ankle? Try the elliptical or the stairs. Bad elbows? Don't do push-ups because a guy on Facebook said so.
It's the same position I'd taken in 2017: weight loss is mostly made in the kitchen, and exercise is for health (video f119qGyJ7AY). In this Live I told people not to "refeed" the exercise if weight loss is the goal (live TFCK5340). Eating back what you burned is a maintenance tool.
The rest of the Live is for the nerds. I said so on camera: if you're a beginner and you stayed until minute 38, you're my tribe (live TFCK5340).
The claim worth unpacking: salt and potassium in your workout water
My suggestion was to start with about 500 mg of sodium and 500 mg of potassium in a litre of water. Cut it in half if it tastes too salty. I said I'd worked up to 2,000 mg of salt and 1,800 mg of potassium per litre for my own kickboxing sessions, and that most people find that mix gross (live TFCK5340). I also read the serving off the potassium-salt label and said not to stack several servings at once.
The electrolytes evidence page gives some context:
- The National Academies set potassium's adequate intake at 2,600 mg a day for women and 3,400 mg a day for men. Sodium's adequate intake is 1,500 mg a day, with advice to cut back if you're above 2,300 mg (NASEM 2019).
- The American Heart Association says its 1,500 mg goal may not apply to people losing large amounts of sodium in sweat (AHA). That matches what I said about heavy sweaters: if your shirt is drenched, you need to replace more.
- WHO suggests potassium-containing salt substitutes in place of regular salt, except for people at risk of high potassium (WHO). In a large trial in rural China, a potassium-enriched salt substitute lowered stroke, major cardiovascular events and death, with no significant difference in serious high-potassium events (Neal et al., 2021).
That exception matters. I said in the Live that too much potassium can affect your heart, and that anyone with a salt-sensitive heart condition or blood-pressure issues should talk to their doctor first (live TFCK5340). I'd add kidney disease, and blood-pressure or diabetes medication, to that list. Those are the cases where a doctor should be involved before you add potassium. See keto with medication.
Then vs now: carbs around training
In 2017 the short version was 10 to 20 g of carbs before and after explosive training, and none for light exercise (video XhEJ9x5sP0g). By 2019 I was talking about calories rather than grams. My ballpark was something like 100 calories of pressed-sugar candies before and after a lifting session, or replacing 60 to 80% of what you burn with fast sugar if you're at maintenance (live TFCK5340). The glycogen figures I gave, about 700 g in a 185-pound man with two grams of water per gram, were my ballpark too. None of the evidence pages measures them.
My prediction that ketone esters would get treated like blood doping was a guess. I labelled it a guess at the time, and nothing here tests it.
The line that holds up
"Diet is what you habitually eat," not one meal or one slice of grandma's cake (live TFCK5340). Eat the cake, go back to your normal food, and don't build a habit of cheating and then trying to work it off.
Key points
- Beginners: get active at all. Walk, take stairs, do body-weight moves, and work around injuries with a trainer if you can.
- Skip new exercise during the first month of keto unless it's already part of your life.
- Cramps, low energy and light-headedness after a workout point to electrolytes. Broth plus a little salt is the easy fix.
- Start small with sodium and potassium in water. Follow the label, and never confuse teaspoons and tablespoons.
- If you have heart, kidney or blood-pressure problems, or take blood-pressure or diabetes medication, talk to your doctor before adding potassium.
- Small doses of sugar around hard training are a maintenance and performance tool. They're not needed for weight loss.
- One off-plan meal is not your diet.
Related
- Guide: do you need to exercise on keto · carbs for hard workouts · sodium · potassium and magnesium · who should talk to a doctor
- Blog: keto workout fatigue · sports drinks and electrolytes · leg cramps on keto · light salt · what happens if you cheat · keto for MMA and combat sports
- Videos: do you need exercise · carbs before a workout · tired on keto: the bouillon routine · exercise and high fat