Blah blah blah, intermittent fasting is an eating pattern that cycles periods of eating and not eating while traditional dieting or continuous energy restriction entails continuously trying to restrict calorie intake. You know all that. Now let’s move on to why you’re reading this post.
You want to know what’s better for weight loss — intermittent fasting (IF) or continuous energy restriction (CER)?
Well, let’s not trust someone who calls herself IntermittentFastingKatie on Instagram, and instead let’s go back in time and go over all the systematic reviews and meta-analyses comparing IF to CER for weight loss outcomes (“all” to my knowledge).
So ingest as much coffee as possible and let’s go.
As far as I know, the study by Seimon RV, et al. was the first study where Seimon said hey intermittent fasting has been all the rage lately so let’s investigate the fugg out of the current data and do a systematic review maybe? A bunch of her colleagues went fugg yeah let’s do that. And investigate they did:
They looked at 40 studies in total, 12 of which directly compared IF and CER. The bunch concluded:
“While intermittent fasting appears to produce similar effects to continuous energy restriction to reduce body weight, fat mass, fat-free mass and improve glucose homeostasis, and may reduce appetite, it does not appear to attenuate other adaptive responses to energy restriction or improve weight loss efficiency <…>. Intermittent fasting thus represents a valid–albeit apparently not superior–option to continuous energy restriction for weight loss.”
IF vs. CER: 1-1. No winners, no losers, let’s move on.
A few months later, Davis and colleagues were like, hang on we’re researchers too we know how to run a systematic review. Run they did:
Their goal was to determine the effectiveness of IF on weight loss in overweight and obese adults and compare it with CER. They found that:
“IER (intermittent energy restriction) resulted in comparable weight loss to DER (daily energy restriction) when overall energy restriction remained similar between diets <…>. IER may be an effective alternative strategy for health practitioners to promote weight loss for selected overweight and obese people.”
IF vs. CER: 2-2. Still no magic properties for IF. Let’s continue.
A few months later Headland M, et al. went all okay off to the lab we go and they did their own systematic review and meta-analysis looking at six studies that directly compared IF to CER:
They were like woohoo fugg yeah the previous researchers were wrong! Oh, wait, we missed a number here. And a few more here. Ok, now we have a conclusion:
“Eight interventions in six trials were used for the meta-analyses, with results indicating neither intermittent or continuous energy restriction being superior with respect to weight loss <…>. IER may be similar to CER and therefore present a successful alternative for individuals who find CER too restrictive in dietary choices during weight reduction.”
IF vs. CER: 3-3. IntermittentFastingKatie isn’t happy.
2018 was interesting. Kanye West acted like an overheated dog and said slavery sounded like “a choice,” Batman’s penis was published in the comics for the first time ever, and a giant 6’3″ Australian cow got more famous than Kanye will ever get.
Ignoring this extraordinary news, Harris and colleagues said fugg the cow and fugg Kanye. Especially Kanye. Let’s do a systematic review and meta-analysis on the effectiveness of IF vs. CER in the treatment of overweight and obesity:
I feel like I wasted too much time talking about Kanye so straight to the results we go:
“Although both treatment interventions achieved similar changes in body weight (approximately 7 kg), the pooled estimate for studies that investigated the effect of intermittent energy restriction in comparison to continuous energy restriction revealed no significant difference in weight loss.”
Brain vs Kanye: 1,000,000:0. IF vs. CER: 4-4.
Coffi l, et al. conducted another systematic review and meta-analysis in 2018. Since it was published on December 24, I assume the researchers were short on time and so their families received a big nothingburger for Christmas. The life of a scientist, I guess. Anyway, the study:
Since Christmas was right around the corner and the researchers didn’t want to waste anyone’s time, they came up with a very short conclusion:
“Both intermittent and continuous energy restriction achieved a comparable effect in promoting weight-loss and metabolic improvements.”
IF vs. CER: 5-5. IntermittentFastingKatie is about to say give me another study like that and Ima block your ass on Gram. Okay then, let’s do another one.
The researcher called Xueting Wei woke up one morning and was like hey it’s 2022 already we have heaps of IF vs. CER studies so why don’t I gather my army of researchers and conduct the biggest systematic review on the matter to date? And that he did:
The researchers concluded that “Compared to continuous energy restriction, intermittent energy restriction showed no significant long-term differences in anthropometric, cardiometabolic, inflammatory, or appetite outcomes in included studies” and then they went home.
IF vs. CER: 6-6. IF isn’t inherently better than traditional calorie restriction for weight loss but… IntermittentFastingKatie isn’t going to let it go because IF worked so well for her and so everyone else should do it.
- Intermittent fasting obviously works. But no better than traditional dieting. It isn’t magic and it doesn’t defy the first law of thermodynamics. The benefits of IF are simply due to spontaneous reduction in overall caloric intake.
- This doesn’t mean IF is useless. It simply means that it can be an alternative tool to regulate food intake and make it easier to stick to a calorie deficit. It may work well for you, it may not. The good thing about IF is that it doesn’t ban any foods from your diet.
- IF can work if you’re a busy, pressured-by-time person, or you prefer fewer but larger meals. IF can also help you differentiate between actual hunger and mental hunger.
- You should probably stay away from IF if you’re pregnant, breastfeeding, have low blood pressure, or have a history of disordered eating. I’m not your doctor so this is in no way intended as medical advice.
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Originally published by me on Medium on April 27, 2023