Why you lose weight when you eat more 🤨

By Elliot Fisher MS, CSCS, PES, NSCA-CPT

Many many years ago when I was dieting I had been tracking my calories and macros consistently and on the dot day in and day out.

I was losing weight consistently about a pound a week for the first month or two.

After that I hit a plateau which will happen to everyone eventually.

So I decreased my calories by 100 and continued to follow the plan.

After two weeks I didn’t lose any more weight. So I decreased my calories by another 100.

Another two weeks went by and I hadn’t lost any weight still. So I had gone a month without losing any weight, while being extra diligent not to cheat or go over my calories or off my macros at all.

At this point I was pretty fed up so I said screw it and had a huge cheat meal. Probably 10,000 calories remembering my old cheats.

The next day I was down 10 pounds.

What happened here?

It’s common to think there’s some magic that the cheat meal increased your metabolic rate and that caused the weight loss.(1)

However it’s extremely unlikely that my metabolism had increased enough to lose 10 pounds overnight.

Before I explain what likely did occur, I want to note that when you’re in a calorie deficit for a prolonged time your basal metabolic rate can decrease a small amount but that your non exercise activity thermogenesis (NEAT) calories will decrease to match your food intake.(2) NEAT calories include the movements you do throughout the day that are not intentional, that are burning calories. Think fidgeting, tapping your foot, clapping your hands, etc. This can change a lot and that will decrease your energy expenditure.

What likely did happen was a fluctuation in water retention. When you’re in a calorie deficit, it’s a stressor on the body. When you’re stressed cortisol increases.(3)

When cortisol levels are elevated you start to hold onto more fluid than usual.(4)

What likely happened was my body was under the constant stress of dieting and was holding on to more and more water weight as I continued to drop my calories.

When I had the cheat meal it was a significant increase in food and my physiology relaxed a bit and cortisol levels decreased. Leading to a significant decrease in body weight.

What we can take away from this is that you should NOT have a cheat meal and think it will help you lose weight. If you’re dieting and not losing weight, be honest with yourself if you’re doing the workouts and cardio and truly following your allotted calories and protein. If you HAVE been doing everything right and not seeing the scale reflect then having a higher calorie day (I recommend eating at your old maintenance calories not a huge cheat day like I had). The increase in calories may be just what you need to break your weight loss plateau.

References:

1. Molé PA. Impact of energy intake and exercise on resting metabolic rate. Sports Med. 1990;10(2):72-87. doi:10.2165/00007256-199010020-00002

2. Chung N, Park MY, Kim J, Park HY, Hwang H, Lee CH, Han JS, So J, Park J, Lim K. Non-exercise activity thermogenesis (NEAT): a component of total daily energy expenditure. J Exerc Nutrition Biochem. 2018 Jun 30;22(2):23-30. doi: 10.20463/jenb.2018.0013. PMID: 30149423; PMCID: PMC6058072.

3. Tomiyama AJ, Mann T, Vinas D, Hunger JM, Dejager J, Taylor SE. Low calorie dieting increases cortisol. Psychosom Med. 2010;72(4):357-364. doi:10.1097/PSY.0b013e3181d9523c

4. Espiner EA. The effects of stress on salt and water balance. Baillieres Clin Endocrinol Metab. 1987;1(2):375-390. doi:10.1016/s0950-351x(87)80068-x