Fast 800 combined with time-restricted eating is working really well for me. I’ve been on it since January except for relaxations most weekends when I eat what I want; and I’ve lost 9 kilos and feel really good. Not really struggling with hunger or dizziness and losing weight steadily. I’m 58, work at a desk and weight 84kgs.

However, I’m often under 800 calories per day and wondering if this is a potential health issue? On days when I have Weetbix with low-fat milk and a small flat white for breakfast (208 calories); and a Saladworks Lentil soup (151 calories) and no dinner (which is 2-3 days per week), I’m topping out at less than 400 calories. I feel no ill-effects or terrible hunger. Any risks from this?

Hi Smithcorp, I am no expert but what you’re describing there looks awfully low in protein, vegetables and healthy fats. I’m concerned that you are not getting the nutrients needed to keep going. You might be fine for a while because you have reserves but long term it doesn’t seem healthy.

In addition, Weetbix are wheat based so generally off the table as they can spike an insulin response. Insulin’s other role is as a fat storage hormone, when it’s high the fat stored in your fat cells can’t be accessed for metabolism. Taken to extreme, in the absence of carbohydrates and proteins in the diet, your body will start using your muscles.

Are you vegetarian? If so, try searching in the search box on the top right, there are many vegetarians here who can give you better advice than I can.

Hi Smithcorp,
I think you may be following the old fashioned idea of calories in / calories out, rather than focusing on keeping carbs low.
The problem is if you eat too high a level of carbs, your insulin levels will remain high so while you will loose weight in the short term your body will eventually decide its in starvation mode and reduce your metabolic rate making it difficult to maintain the lower weight. – There is an American tv program called The Greatest Loser. The reason they never have a reunion / follow up program is that all the participants bar one regained more weight than they lost over the year of calorie counting and exercise. (The one exception did regain weight and then had bariatric surgery to reduce the size of his stomach).
If you keep your daily intake of carbs low, so that insulin levels remain low you will enable your body to freely access your fat stores, while not triggering the “starvation” response which causes the reduction of your metabolic rate.
I would recommend using one of the apps you can install on a mobile phone. I use fatsecret, to record all you eat each day. Aim initially for 50g of carbs per day, 0.6g to 0.8g of protein per kilo of TARGET body weight and make up the rest of your calories from healthy fat.
I also have found that eating this way I don’t always eat 800 calories a day, but providing your carbs are low enough so that you are in ketosis (fat burning mode) that doesn’t matter too much.

Thanks all for the replies. I’ll drop the weetbix and eat more eggs and salads and pay better attention to the carbs.